【问】 我在一本语法书上遇到这样两个句子：
 1. You need not be afraid of being punished.
 2. He is afraid to do it.
 但是，该书并没有对afraid of doing与afraid to do这两个结构在语义和用法上进行区别。
 【答】 afraid of doing与afraid to do这两个结构在语义上是有区别的。afraid of doing是指“担心、害怕会发生某事，”(worried or anxious about sth.which might happen)，例如：
 1. He is not afraid of dying.
 他不怕死。
 2. She seems awfully afraid of losing her job. (LDCE)
 她好象特别害怕失去她的工作。
 afraid to do则是指“由于害怕而不愿去做某事”(unwilling to do sth.because you are fright-ened)。be afraid to do sth.=fear to do sth.(害怕做某事)，例如：
 1. Don’t be afraid to ask questions. (ECD)
 不要不敢提问题。
 2. She was afraid to leave her room.
 她不敢离开她的房间。
 3. She was afraid to see you again. (Shaw)
 她不敢再见你了。
 4. He was afraid to take even a drink of water. (Sinclair)
 他甚至连水也不敢喝。
 5. She was afraid to wake her husband. (ECD)
 她不敢叫醒丈夫(可能是由于害怕丈夫生气而不敢叫醒他)。
 6. Even fools are afraid to lean against a rotten post.
 连傻瓜也不敢倚在朽烂的柱子上。
 7. He was afraid to show his emotions.
 他害怕表露出自己的情感。
 8. We are afraid to walk in the park at night since the woman was killed there. (URW)
 自从那位妇女在公园被杀以来，我们夜里不敢去公园散步了。