afraid of doing與afraid to do的用法和區別

問：我在一本文法書上遇到這樣兩個句子:
1. You need not be afraid of  being punished.
2. He is afraid to do it.
但是, 該書並沒有對afraid of doing 與afraid to do 這兩個結構在語意和用法上進行區別。

答：afraid of doing 與afraid to do 這兩個結構在語意上是有區別的。

afraid of doing 是指“擔心、害怕會發生某事”(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. 她好像特別害怕失去工作。

afraid to do 則是指“由於害怕而不願去做某事”(unwilling to do sth. because you are frightened) 。be afraid to do sth. = fear to do sth. (害怕做某事), 例如:

1. Don’t be afraid to ask questions. 不要不敢提問題。
2. She was afraid to leave her room. 她不敢離開自己的房間。
3. She was afraid to see you again. 她不敢再見你了。
4. He was afraid to take even a drink of water. 他甚至連水也不敢喝。

[附注] 當be afraid of 後接的動名詞表示意志所致的行為時, 它也可能表示“(因擔心其後果) 而不敢去做某事”:

I’m afraid of telling / to tell her the truth.
我不敢告訴她實情。

另見：afraid 在這裡作“害怕”解嗎? 和 形容詞afraid 與形容詞frightened 有何區別?