1、be afraid of sth (sb) 害怕某事(某人)。如：
Are you afraid of dogs? 你害狗嗎？
There’s nothing to be afraid of. 沒什么可害怕的。
比較：
He is afraid of her. 他怕她。
He is afraid with her. 跟她在一起時，他很害怕。
2、be afraid of doing sth
(1) 擔心會發(fā)生某事或某情況(但實際上未必會發(fā)生)。如：
She was afraid of waking her husband. 她怕吵醒她丈夫。
I was afraid of hurting her feelings. 我怕傷害她的感情。
注：be afraid of doing sth 表示擔心會發(fā)生某事或某情況時，其后也可用 be afraid that 替換。如：
He was afraid of losing face. =He was afraid (that) he’d lose face. 他怕失面子。
(2) 害怕做某事或不敢做某事(指缺乏勇氣或害怕其后果而不敢)。如：
I’m afraid of telling her. 我不敢告訴她。
He was afraid of jumping. 他不敢跳。
3、be afraid to do sth 害怕做某事或不敢做某事。如：
He was afraid to fly in a plane. 他不敢坐飛機。
He was afraid to go into the house and meet his father. 他不敢進屋去見他父親。
注：以上兩類句型的異同之處：表示擔心會發(fā)生某事或某情況，只能用 be afraid of doing sth, 而表示害怕做某事或不敢做某事等，則兩者都可用。如：
Don’t be afraid to ask [of asking] question. 不要害怕問問題。
He is afraid to go out [of going out] alone at night. 他不敢晚上一個人出去。