1. Common Sense Science of Life

1.50 Little Science Knowledge of Common Sense

1. Rabbits use their legs to slap the ground to convey information, and use their hind legs to convey information. Most of the ones that slap the ground are male rabbits, which is a way for them to express their emotions to female rabbits. 2. The largest monkey in the world is the baboon, and the smallest monkey is the tamarin. 3. The real name of "Four Unlike" is Elk is a rare animal in my country. 4. Why does ice cream steam? The reason why the ice cream steams is because there is a lot of invisible water vapor in the outside air. When it comes into contact with very cold ice cream, it will liquefy into mist droplets and surround the ice cream when it gets cold. It looks like the ice cream is "steaming".

5. Why do sunflowers always face the sun? The stems of sunflowers contain a wonderful auxin. This auxin is very photophobic.

When it encounters light, it will go to the backlight side. At the same time, it also causes the cells on the backlight side to multiply rapidly. Therefore, the backlight side grows faster than the side facing the light, making the cells on the backlight side grow faster. Sunflowers are phototropically bent. 6. Why do cicadas shed their skin? The cicada's outer shell (exoskeleton) is hard and cannot expand as the cicada grows. When the cicada grows to a certain stage, the cicada's exoskeleton limits the growth of the cicada. The cicada takes off its original exoskeleton, which is the process of shedding. .

7. How do bees make honey? The bee first vomits the sweet juice of the collected flowers into an empty hive. At night, it sucks the sweet juice into its honey stomach to prepare it, then spits it out, and then swallows it. In this way, it takes 100 times to spit out the sweet juice. ~240 times, finally it becomes sweet honey. 8. Why do stars twinkle? We see stars twinkling, not because of changes in the luminosity of the stars themselves, but because of the obstruction of the atmosphere.

The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent; its transparency varies depending on density.

So when we look at the stars through it on the ground, we will see that the stars seem to be twinkling. 9. Why do people yawn? When we feel tired, our bodies have produced a lot of carbon dioxide.

When there is too much carbon dioxide, oxygen must be added to balance the needs of the body. Because these residual carbon dioxide will affect the functional activities of our body, the body will issue a protective response and yawn.

Yawning is a deep breathing action, which allows us to take in more oxygen and expel carbon dioxide than usual, and also eliminates fatigue. 10. Why can snakes walk without legs? Snakes have many scales on their bodies, which are their outermost layer of armor.

The scales are not only used to protect the body, but also serve as their "feet". When a snake crawls forward, its body forms an S shape.

Each scale on the outside of the S-shape will tilt up to help the snake grasp uneven roads as it moves forward. These scales cooperate with the snake's muscles and can push the body forward, so the snake can move without legs! 11. Why does people’s hair turn gray as they get older? There is a substance called "melanin" in our hair. The more melanin, the darker the color of the hair.

If there is less melanin, the hair will turn yellow or white. When humans reach old age, various body functions will gradually decline, and the formation of pigment will become less and less, so the hair will gradually turn white! 12. Why do fireflies glow? Fireflies emit light because they have luminescent devices at the end of their abdomens. The luminescent devices are filled with many phosphorus-containing luminescent substances and luminescent enzymes, allowing fireflies to emit flashes of light.

The purpose of fireflies’ light is not only for lighting, but also for courtship, warning, and trapping. This is also a tool for them to communicate. Different types of fireflies have different lighting methods, lighting frequencies and colors, and they use this to convey different messages.

13. Why does your stomach growl when you are hungry? Your stomach will growl when you are hungry. This is because the food you have eaten is almost finished digesting. Although your stomach is empty, gastric juice will continue to be secreted.

At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will stir up, causing a gurgling sound.

Don’t be embarrassed by your stomach growling next time! Because this is a normal physiological action. 14. Why can’t ostriches fly? They are a type of giant ostrich bird, but they cannot fly into the sky! This is not because their wings don't work, but because their feathers are too soft and their wings are too small, not suitable for flying at all.

In addition, the muscles of the ostrich are underdeveloped and the sternum is flat, which is not helpful for flying. Ostriches live in Africa. Since they have lived in desert areas for a long time, their bodies have gradually evolved into what they are now in order to adapt to the environment.

15. Why does food in cans not go bad easily? Luncheon meat, dace with black bean sauce, and beans in tomato sauce.

These are delicious canned foods that can be stored for a long time without spoiling easily. This is because the can is sealed and bacteria cannot enter.

When people make canned food, they take all the air out of the can and then seal it. In the absence of air, even if there are a few bacteria on the food inside, they cannot survive or reproduce! 16. Why do babies cry non-stop when they are born? Babies cry loudly when they are born. This is not because they are unhappy, but because they are taking their first breath of air! When a baby is born out of its mother's body, the first breath of air they inhale rushes to the throat, which violently impacts the vocal cords, causing them to vibrate and make a cry-like sound.

17. Why does the lizard’s tail still bounce after being broken off? In order to protect themselves, many lizards also use protective colors to hide their appearance. When some lizards are attacked, their tails will break off due to violent muscle contraction. Since some of the nerves in the broken tail are still alive, it will continue to bounce, thus distracting the enemy so that they can escape.

Don’t think that their lives will end like this. In fact, it only takes a few months for their tails to grow back and continue their lives. 18. Why do squirrels have such big tails? Don't look at the squirrel's tail! While the squirrel is jumping up and down the tree, its tail is doing a great job.

It allows the squirrel to balance when jumping on the tree and avoid falling and being injured. In addition, this big tail can also play a protective role in winter, tightly surrounding the squirrel's body, which is both convenient and practical.

19. Why can’t people’s thumbs have one or three joints? The average person has five fingers, and the length of the fingers.

It will become magnetized water. Magnetized water has various magical effects and is widely used in industry, agriculture, medicine and other fields. In industry, people initially only used magnetic fields to treat a small amount of boiler water to reduce scale. Now magnetized water It has been widely used in the cooling systems of various high-temperature furnaces, playing an important role in improving cooling efficiency and extending the life of the furnace. Many chemical plants use magnetized water to speed up chemical reactions and increase output. The construction industry uses magnetized water to stir concrete. The strength of concrete is greatly improved. Textile factories use magnetized water to remove slurry, and printing and dyeing factories use magnetized water to mix colors, both of which have achieved good economic benefits. In agriculture, using magnetized water to soak seeds and raise seedlings can make the seeds germinate quickly and have a high germination rate. , seedlings have the advantages of plant height, stem thickness, root length, etc.; using magnetized water to irrigate fields can loosen the soil, accelerate the decomposition of organic fertilizers, and improve the growth of crops. Through practice, people have found that soybeans, corn, etc. that are often irrigated with magnetized water The yield of crops and vegetables such as radish and cucumber can be increased by 10 to 45%, and the yield of rice, wheat, rapeseed and other crops can be increased by 11 to 18%. In addition, some livestock farms use magnetized water to feed poultry and livestock, which can reduce livestock diseases and increase weight faster. . In medicine, magnetized water can not only kill a variety of bacteria and viruses, but also treat a variety of diseases. For example, magnetized water can treat various stone diseases (gallstones, bladder stones, kidney stones, etc.), stomach problems, high blood pressure, It is effective for treating diabetes and colds. For people who are not sick, regular drinking of magnetized water can also play a role in disease prevention and fitness. In daily life, washing clothes with magnetized washing powder solution can wash clothes more efficiently. Clean. Interestingly, the washing effect is also very satisfactory when using magnetized water instead of washing powder. Why does magnetized water have such a magical effect? This is a mystery that has not yet been revealed. Some scientists believe that the water molecule itself is a small magnet. Since opposite magnetic poles attract each other, many water molecules in ordinary water will first attract each other and connect to form a huge "molecular cluster". This This kind of "molecular cluster" will weaken various physical and chemical properties of water. When ordinary water passes through the magnetic field, it breaks through the originally connected "molecular cluster" and turns it into a single active water molecule. Of course, it must be thoroughly exposed The secret to unlocking magnetized water.

3. A complete collection of daily life science tips

1. If you eat something spicy and feel like it will kill you, put a little salt in your mouth, hold it in your mouth, and spit it out. If you have yellow teeth, you can chew peanuts and hold them in your mouth and brush your teeth for three minutes. It is very effective. 3. If there is a small area of ??skin damage or burns or scalds, wipe Applying a little toothpaste can immediately stop bleeding and relieve pain; 4. Often there are unsightly tea stains left in the tea cups, wash them with toothpaste and they will be very clean; 5. Open your mouth slightly when you nod eye drops, so that your eyes will not be messed up. Blinked; ?6. If you have an ulcer in your mouth, stick it on the ulcer with vitamin C. After it dissolves, the ulcer will be basically healed; ?7. If there is small dust in your eyes, close your eyes and cough hard a few times, and the dust will disappear. Come out on your own; ?8. After washing your face, use your fingers to dip some fine salt into the nose and rub it gently on both sides of the nose, then rinse with water. Blackheads and acne will be removed, and the pores will become smaller; ?9 .When you have just been bitten by a mosquito, apply soap and it will not itch; 10. If your throat or gums are inflamed, cut the watermelon into small pieces at night and eat it with salt. Remember to do it at night, then the symptoms will disappear. It will be relieved and it will be fine the next day; ?11. Blow the hair dryer on the label until the glue of the label is hot, and then you can easily peel off the label; ?12. If you are afraid of wrinkles when bringing clothes while traveling, You can roll every piece of clothing into a roll; ?13. Drink some vinegar when you burp, and you will see immediate results; ?14. If you eat something with a peculiar smell, such as garlic or stinky tofu, just eat a few peanuts and it will be fine ; ?15. To treat coughs, especially dry coughs, fry eggs with pure sesame oil before going to bed at night. Add a little more oil. Do not add any seasonings. Eat it while it is hot and then go to bed. The effect will be obvious after taking it for a few days. ; ?16. If a girl with thick wrists wants to wear a thinner bracelet, she should not wear it forcefully. She should put a plastic bag on her hand and then put the bracelet on. It is very easy to wear and will not cause pain to her hand. It is also the same when taking it off. Method; ?17. Chestnut skin is difficult to peel. Peel off the shell first, then put it in the microwave oven for a while. Take it out and rub it while it is hot. The skin will fall off; ?18. When arranging flowers, add a drop of it to the water. Dishwashing liquid can last for several days; ?19. Put the walnuts into the pot and steam for ten minutes, take them out and put them in cold water and then smash them open, and you can take out the complete peach kernels; ?20. Put the shrimps in a bowl In it, add a little refined salt and edible alkali powder, rub it with your hands for a while, soak it in water, and then rinse it with water. The fried shrimps will be as transparent as crystal, tender and delicious; ? 21. When frying the meat, first Soak the meat in baking soda water for ten minutes, pour out the water, and then add the flavor. It will be very tender when fried; ?22. Soak the remaining tea leaves in water for a few days, and then pour it on the roots of the plants to promote plant growth; ?23. Drying the tea leaves and burning them in toilets or ditches can eliminate the odor and have the function of driving away mosquitoes and flies; ? 24. Recooking rice with raw rice: Use chopsticks to poke some holes in the rice that go straight to the bottom of the pot, and sprinkle in a little rice wine to re-cook it. Stew, ? 25. If only the surface is cooked, just flip the surface to the middle and simmer again; ? 26. How to remove greasiness from screen windows: put the cigarette butts left from washing clothes and smoking together in the water, and wait until they dissolve. The effect of cleaning glass windows and screens is really good; ?27. Just put a small piece of chalk in the jewelry box to keep the jewelry shiny; ?28. Use wind oil to remove the adhesive marks on the surface of tables and bottles. It can be wiped; ?29. Always carry a small dry battery in your bag when you go out. If your skirt has static electricity, rub the positive terminal of the battery on the skirt a few times to remove the static electricity; ?30. No matter where the shoe is scratched For your feet, just apply a little bit of white wine on the areas where your shoes rub your feet to ensure that they don't rub your feet; 31. When cooking vegetables, if they must be blanched, it's best to use the water used to blanch the vegetables as much as possible.

For example, when making dumplings, an appropriate amount of blanched water can be put into the meat filling, which not only ensures nutrition, but also makes the dumpling filling delicious and soupy; ?32. Feet are prone to sweating in summer, so use it every day Soaking your feet in light salt water can effectively deal with sweaty feet; ?33. Sunbathing after swimming in summer can prevent skin strain and other diseases; ?34. Pillows are prone to moisture and mold growth in summer, and frequent exposure to the sun is good for your health; ?35. Eat more Barley and adzuki bean porridge and other moist foods can strengthen the spleen and prevent heatstroke; 36. Prevent insomnia: talk less before going to bed, avoid drinking strong tea, do not use your brain before going to bed, and wash your feet with hot water and vinegar; 37. Honeysuckle It has the effect of dispersing rheumatism. Decoction the juice of honeysuckle and mix it with honey to relieve summer heat. ?38. Drinking tea after eating too fatty food can stimulate the autonomic nervous system and promote fat metabolism. ?39. Lack of sleep will cause To become stupid, you need eight hours of sleep a day, and having a nap habit can delay aging; ?40. Your hands can easily become dry and rough, so soaking your hands in vinegar for ten minutes can help protect your skin; ?41. In summer, wipe your mat with clean water with toilet water added. The mat can keep the mat fresh and clean. Of course, it is best to wipe along the lines of the mat, so that the toilet water can penetrate into the lines and gaps of the mat, so that the cool and comfortable feeling will last longer; 42. Eat more tomatoes, citric acid and other acidic vegetables and fruits for breakfast, which is good for nourishing the liver ; ?43. Refreshing and anti-itching. When washing your hair or taking a bath, add five or six drops of toilet water in the water, which can have a good cooling effect, remove bacteria, remove prickly heat and relieve itching; ?44. Grapes contain sleep-auxiliary hormones, and regular consumption can help sleep ?45. Drinking more tomato soup in summer can not only obtain nutrients, but also replenish water. Tomato soup should be cooked and cooled before drinking. The lycopene contained in it has certain effects on fighting prostate cancer and protecting myocardium. It is most suitable for Men; Brushing your teeth immediately after eating acidic substances will damage your dental health; ?46. When the skin is broken due to trauma, apply toothpaste on the injured area to reduce inflammation and stop bleeding, and then bandage it. As a temporary first aid drug, medicated toothpaste is the most effective; ?47 .Spray white vinegar on the cutting board and leave it for half an hour before washing it. It can not only sterilize but also remove odor; 48. Drinking yogurt can relieve irritability after hangover. Yogurt can protect the gastric mucosa, delay alcohol absorption, and contains calcium. Rich in alcohol, it is especially effective in relieving irritability after drinking; ?49. When the foreskin of leather shoes has been stored for a long time and becomes moldy, you can use a soft cloth dipped in alcohol and water (1:1) solution to wipe it; ?50. When you have a headache or dizziness, you can apply it on the temples Use toothpaste, because toothpaste contains menthol and clove oil, which can relieve pain; ?51. Freeze candles for 24 hours before inserting them into the birthday cake. The candle oil will not flow when lit; ?52. White clothes and pants are easy to wash after washing For yellowing, you can take a basin of water, add two or three drops of blue ink, soak the washed clothes for a quarter of an hour, do not wring them out, just put them in the sun to dry them, and they will become white and clean; ?53.

4. Little science knowledge

Why do stars twinkle? We see stars twinkling, not because of changes in the luminosity of the stars themselves, but because of the obstruction of the atmosphere. The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere.

The atmosphere is not absolutely transparent. Its transparency will change depending on the density. So when we look at the stars through it on the ground, we will see that the stars seem to be twinkling.

2. Why do people yawn? When we feel tired, our bodies have produced a lot of carbon dioxide.

When there is too much carbon dioxide, oxygen must be added to balance the needs of the body. Because these residual carbon dioxide will affect the functional activities of our body, the body will issue a protective response and yawn.

Yawning is a deep breathing action, which allows us to take in more oxygen and expel carbon dioxide than usual, and also eliminates fatigue. 3.

Why can snakes walk without legs? Snakes have many scales on their bodies, which are their outermost layer of armor. The scales are not only used to protect the body, but also serve as their "feet".

When a snake crawls forward, its body will form an S shape.

Each scale on the outside of the S-shape will tilt up to help the snake grasp uneven roads as it moves forward.

These scales cooperate with the snake's muscles and can push the body forward, so the snake can move without legs! 4. Why do sunflowers always bloom toward the sun? The stems below the sunflower discs contain a substance called "auxin."

This substance has the function of accelerating reproduction, but it is optically repulsive. Whenever it encounters light, it will run to the backlight side. Therefore, when the sun rises, the sunflower stems immediately hide to the backlight side, and it seems that the entire plant is bent toward the direction of the sun.

5. Why does hair turn gray as people age? There is a substance called "melanin" in our hair. The more melanin, the darker the color of the hair.

If there is less melanin, the hair will turn yellow or white. When humans reach old age, various functions of the body will gradually decline, and the formation of pigment will become less and less, so the hair will gradually turn white! 6.

Why do fireflies glow? Fireflies emit light because they have luminescent devices at the end of their abdomens. The luminescent devices are filled with many phosphorus-containing luminescent substances and luminescent enzymes, allowing fireflies to emit flashes of light. The purpose of fireflies' light is not only for lighting, but also for courtship, warning, and trapping.

This is also a tool for them to communicate. Different types of fireflies have different lighting methods, lighting frequencies and colors, and they use this to convey different messages. 7.

Why does my stomach growl when I am hungry? Your stomach will growl when you are hungry. This is because the food you have eaten is almost finished digesting. Although your stomach is empty, gastric juice will continue to be secreted. At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will stir up, causing a gurgling sound.

Don’t be embarrassed by your stomach growling next time! Because this is a normal physiological action. 8.

Why can’t ostriches fly? They are a type of giant ostrich bird, but they cannot fly into the sky! This is not because their wings don't work, but because their feathers are too soft and their wings are too small, not suitable for flying at all. In addition, the muscles of the ostrich are underdeveloped and the sternum is flat, which is not helpful for flying.

Ostriches live in Africa. Since they have lived in desert areas for a long time, their bodies have gradually evolved into what they are today in order to adapt to the environment. 9.

Why does food in cans not go bad easily? Luncheon meat, dace with black bean sauce, and beans in tomato sauce.

These are delicious canned foods that can be stored for a long time without spoiling easily. This is because the can is sealed and bacteria cannot enter.

When people make canned food, they take all the air out of the can and then seal it. In the absence of air, even if there are a few bacteria on the food inside, they cannot survive or reproduce! 10.

Why do babies cry non-stop when they are born? Babies cry loudly when they are born. This is not because they are unhappy, but because they are taking their first breath of air! When a baby is born out of its mother's body, the first breath of air they inhale rushes to the throat, which violently impacts the vocal cords, causing them to vibrate and make a cry-like sound. 11.

Why does a lizard still bounce after its tail is broken off? In order to protect themselves, many lizards also use protective colors to hide their appearance. When some lizards are attacked, their tails will break off due to violent muscle contraction. Since some of the nerves in the broken tail are still alive, it will continue to bounce, thus distracting the enemy so that they can escape.

Don’t think that their lives will end like this. In fact, it only takes a few months for their tails to grow back and continue their lives. 12.

Why do squirrels have such big tails? Don't look at the squirrel's tail! While the squirrel is jumping up and down the tree, its tail is doing a great job.

It allows the squirrel to balance when jumping in the tree and avoid falling and being injured.

In addition, this big tail can also play a protective role in winter, tightly surrounding the squirrel's body, which is both convenient and practical. 13.

Why can’t people’s thumbs have one or three joints? The average person has five fingers, and the lengths of the fingers vary. However, has anyone noticed that except for the thumb, other fingers also have three joints, but the thumb only has two joints? It turns out that its number of segments matches the other four fingers.

If it has three joints, the thumb will be weak and cannot lift heavier objects; if it has only one joint, it will not be able to cooperate with the other four fingers to grasp things freely! 14. Why don't I feel itchy when I scratch myself? When others scratch ourselves, we feel itchy and laugh constantly; however, when we scratch ourselves, we not only don’t laugh, but also don’t feel itchy.

Based on our mental preparation, the brain will send a message that "there will be no danger", and the nerves will relax accordingly, so we will not laugh or feel itchy! 15. Why is the sea water mostly blue or green? Looking at the sea, we often find that the water is blue or green.

However, when you pick up the seawater, you can only see that it is as transparent and colorless as the water in the past. Original.

5. What is the difference between scientific knowledge and common sense?

Usually when we say that a person is very knowledgeable, do we mean scientific knowledge or common sense? What is the difference between scientific knowledge and common sense? Let’s find out through comparison. A. In the northern hemisphere, the solar altitude angle in summer is greater than the solar altitude angle in winter. B. The sun is stronger in summer than in winter. Conclusion: A is scientific knowledge, B is common sense in life. If you know A , that means you have a lot of scientific knowledge, which is real knowledge; if you don’t know A, but know B, it means you understand common sense of life, but lack scientific knowledge, that is, you are not very knowledgeable. Analysis: Say "In the Northern Hemisphere , the solar altitude angle in summer is greater than the solar altitude angle in winter." This is scientific knowledge because: (1) This statement can withstand observation and verification and does not change with changes in weather and climate; (2) "The solar altitude angle "(the angle between the line connecting the observation point and the sun and the horizon) is clearly defined than "severe", and repeated observations can be made, and then the results can be compared. (3) The applicable condition "in the northern hemisphere" is very necessary, but it is not necessary if it is in the southern hemisphere. This phenomenon exists. It can be seen that the statement "the sun is stronger in summer than in winter" is just common sense, not scientific knowledge. "Scientific knowledge" is more able to withstand the test of further observation and experiment than "common sense", and is more inclined to It is prepared to accept corrections from others, has clearer applicable conditions, and is foreseeable and universal.

6. A complete collection of scientific knowledge (30 words)

Scientific common sense in life:

1. Why does ice cream steam?

The reason why ice cream steams is because there is a lot of water vapor in the outside air that is invisible to the eyes. When it comes into contact with very cold ice cream, it liquefies into mist droplets and surrounds the ice cream when it gets cold, making it look like ice cream. Same as "gasping".

2. Why do sunflowers always face the sun?

The stems of sunflowers contain a wonderful auxin. This auxin is very photophobic. When exposed to light, it will go to the backlight side, and at the same time it will cause the cells on the backlight side to multiply rapidly. Therefore, the backlight side will grow faster than the light side, causing the sunflower to develop a phototropic bend. .

3. Why do cicadas shed their skin?

The cicada’s outer shell (exoskeleton) is hard and cannot expand as the cicada grows. When the cicada grows to a certain stage, the cicada’s exoskeleton limits the growth of the cicada, and the cicada will expand its original structure. When the exoskeleton is taken off, it becomes the cicada.

4. How do bees make honey?

The bee first spits the sweet juice from the flowers into an empty hive. At night, it sucks the sweet juice into its honey stomach to prepare it, then spits it out, and then swallows it. This hesitation takes 100 to 240 times before it finally becomes sweet honey

5. When the quartz clock hung on the wall stops moving due to exhaustion of battery power, its second hand often stops. At the "9" position on the dial. This is because the second hand is most hindered by the gravity moment at the "9" position. Scientific knowledge

6. Sometimes when the water pipe is discharging water from a nearby faucet, bursts of sound occasionally occur. This is because the water pipes vibrate when water rushes out of the faucet.

7. When taking pictures in front of the TV screen, you should turn off the camera flash and indoor lighting, so that the picture will be clearer. Because the reflected light of flash and lighting on the TV screen will interfere with the transmitted light of the TV picture.

8. Frozen meat thaws faster in water than in air of the same temperature. A hot iron nail cools faster when placed in water than in air of the same temperature. A cup filled with scalding boiling water cools faster when immersed in water than when immersed in air of the same temperature. These phenomena all show that the heat transfer property of water is better than that of air.

9. When the pot is filled with cold water, the water droplets attached to the outer surface of the bottom of the pot will take a long time to dry on the flame, and until It will not boil even if it is boiled dry. This is because the water droplets, the pot and the water in the pot maintain heat conduction and have roughly the same temperature. As long as the water in the pot does not boil, the water droplets will not boil either. The water droplets evaporate on the flame and are gradually burned. Dry.

10. An aliased mirror will become skewed the farther away you are from the mirror. Because the image in the mirror is formed by the reflection of the silver-plated surface behind the mirror, uneven silver-plated surface or uneven glass thickness will cause aliasing. . For a mirror that is out of shape, the further away a person is from the mirror, the greater the deviation of the reflected light from the silver-plated surface from the normal position due to the principle of light amplification, and the more out of shape the mirror will be.