1 . be afraid of sth 害怕某件事。如：
Are you afraid of dogs? 你害狗吗?
There’s nothing to be afraid of. 没什么好害怕的。
较为：
He is afraid of her. 他害怕她。
He is afraid with her. 跟她在一起时，他非常害怕。
2 . be afraid of doing sth
担心会发生某件事或某些情况。如：
She was afraid of waking her husband. 她怕弄醒她的丈夫。
I was afraid of hurting her feelings. 我怕伤害她的爱情。
注：be afraid of doing sth 表明担心会发生某件事或某些情况时，之后还可用 be afraid that 更换。如：
He was afraid of losing face. =He was afraid he’d lose face. 他害怕失脸面。
害怕做某事或不敢做某件事。如：
I’m afraid of telling her. 不敢跟她说。
He was afraid of jumping. 也不敢跳。
3 . be afraid to do sth 害怕做某事或不敢做某件事。如：
He was afraid to fly in a plane. 也不敢乘飞机。
He was afraid to go into the house and meet his father. 也不敢进家去看他爸爸。
注：之上两大类句式的差异的地方：表明担心会发生某件事或某些情况，只能用 be afraid of doing sth, 而表明害怕做某事或不敢做某件事等，则它们都可以用。如：
Don’t be afraid to ask [of asking] question. 不必害怕提问题。
He is afraid to go out [of going out] alone at night. 也不敢晚上一个人出来。