Recall that profit maximization occurs at MR=P(1-1/|E|)=MC, whether in monopolistic or competitive pricing.

Thus a more accurate statement would be:"a monopolistic firm charge when |E|>1 and competitive firm charge at |E|→∞."

Think: When |E|<1, the monopolist can always raise his price to increase revenues, which implies that |E|<1 is not a profit maximizing portion. Also, any competitor faces a flat demand, ie. |E|→∞.

同意你的看法,题目是错的.

当|Ed|<1时,MR=P(1-1/|Ed|)<0 ,不符合MR=MC的利润最大化条件.

但是,当|Ed|<1时,仍有可能P>AC,从而利润>0