① The demand curve of eggs is downward sloping, so the price drops and the corresponding demand increases, so the demand increases.

(2) The relationship between eggs and pigs is substitution, so the demand for eggs increases, which makes the demand for pigs decrease, the demand curve moves to the left, and the equilibrium intersecting with the supply curve moves to the lower left, and the price drops.

③ The relationship between grain (i.e. feed) and pigs is complementary, and the increase of grain price leads to the decrease of grain demand (the principle is the same as ①). The reason for the decrease in food demand is that pigs eat less. Why? Because the supply of pigs is small = = the supply curve shifts to the left.

Typing is so tiring ~