Why are there two ways? (1) adopts the method of digging from both ends to the middle at the same time, because Juyongguan Mountain is high and behind the rock stratum.
(2) Shaft excavation is adopted, because the length of Badaling Tunnel is about 1 100 meters, which is three times that of Juyongguan.
Why does the hot compressor work outside the refrigerator? Of course, it has to dissipate heat.
Refrigerators use evaporative cooling or gasification to absorb heat to achieve the purpose of refrigeration.
Freon is pressurized by the compressor in gaseous state, then flows to the condenser at the back of the refrigerator through the throat, is cooled by the radiator (the temperature of the substance will rise after being compressed), and then condenses into liquid.
After the liquid freon enters the valve of the evaporator, it immediately becomes steam because it is out of the pressure of the compressor, and at the same time absorbs the latent heat of vaporization from the air and food in the refrigerator, resulting in the internal cooling of the refrigerator.
The vaporized freon is pressed back to the condenser outside the box by the compressor to dissipate heat, and then becomes liquid, so the heat energy in the refrigerator is pumped out of the box.
Why are men in two States before marriage and after marriage? Grandson before marriage, father after marriage.
Why are bird droppings two colors? Black is feces and white is urine.
Birds have no bladder, their rectum is extremely short, and they need a lot of water for long-term flight, so their urine is highly concentrated.
Why are there two forms of human form in haunters? Haunters is the city commander of Bopai City. The robot of the same model as Optimus Prime is Optimus Prime's good friend. Because of Megatron's attack, it was also transformed by Alpha Trion. The white one is just the white version of Optimus Prime,
The blue form is equipped with an open-frame truck, which becomes bigger and stronger. Haunters is a born soldier and the designated successor of Optimus Prime. Unfortunately, he was dismembered by Galvatron and his gang, and Matrix didn't choose him as the commander-in-chief.
Why are there two situations instead of three? One is to increase the roots of the fractional equation, and the other is to get different numbers on both sides of the equation. When finding the root, the value of the unknown quantity obtained after solving the whole trial equation is substituted into the simplest common denominator obtained when the denominator is removed on both sides of the equation. If the value of this simplest common denominator is 0, it is the increase of the original equation and is discarded. On the contrary, it is the root of the original equation. Another test method is to substitute it into the original equation to see if the values on the left and right sides of the original equation are equal. A: There is no solution to this equation. An equation of increasing order must have no solution, but the equation without solution is not necessarily the increase of roots. For example, 2x of x is equal to 5, so the two sides of the equation are not equal, so this equation has no solution.
Why is it hot outside the refrigerator? Come on! Urgent need! Of course, if the compressor is to work, it must dissipate heat. On the contrary, when a gas becomes a liquid, it gives off heat. How does the refrigerator arrange these two state changes to achieve the purpose of refrigeration? )
Refrigerator uses evaporative cooling or gasification to absorb heat to achieve the purpose of refrigeration.
In the throat of the refrigerator, there is a refrigerant called freon, commonly known as snow seed. Commonly used is difluoromethane (CCL2F2), which is a colorless, odorless and nontoxic gas with a boiling point of 29℃.
When the freon is in the gaseous state, it is pressurized by the compressor, as shown in the following figure. After being pressurized, it flows to the condenser at the back of the refrigerator through the throat, is cooled by the radiator (the temperature of the substance will rise after being compressed), and then condenses into liquid.
After the liquid freon enters the valve of the evaporator, it immediately becomes steam because it is out of the pressure of the compressor. At the same time, it absorbs the potential evaporation of air and food in the refrigerator, which leads to the internal cooling of the refrigerator.
The vaporized freon is pressed back to the condenser outside the box by the compressor to dissipate heat, and then becomes liquid, so that the heat energy in the refrigerator is pumped out of the box.
Creo two-dimensional datum plane is two straight lines. Personally, I think it is represented by two lines to prevent it from being mistaken for the outline of the part.
Why are Tiger brand safes two trademarks? First of all, every product of every company will not have only one trademark. As for Procter & Gamble, at its peak, there will be 200 brands on the market at the same time, which means that it has 200 trademarks in use at the same time. If there is only one trademark, it will be closed down if it is not operated well once. Therefore, each company will basically have more than two brand trademarks. Hope to adopt