NO.PZ2023010401000036
问题如下：
In perfectly competitive industries, what is the most likely long-run effect of a permanent decrease in demand?选项：
A.Price decreases. B.Firms incur economic losses. C.The number of firms decreases.解释：
A permanent decrease in demand in a perfectly competitive industry will in the short-run cause the demand curve to shift to the left, causing prices to fall. However, in the long-run, firms will leave the industry due to economic losses. As firms leave the industry, supply decreases (i.e., the supply curve shifts left-ward) thus increasing prices back to the equilibrium where economic profit is zero.就像解答中说的，demand curve向左移动
