不是做状语，是宾语
be afraid to do sth与be afraid of doing sth的区别：
1）be afraid to do sth，不敢去做某事 ，强调不敢。
Trust your ability.Don't be afraid to speak. Don't be trapped by shyness.
相信你的能力，不要害怕说，不要被羞怯困住。
So don 't be afraid to speak up.
所以不要害怕说出自己的观点。
2）be afraid of doing sth,一向害怕做某事，表示习惯，强调害怕。
Don't be afraid of speaking up.
别怕，大胆地说。
It's all over. There's nothing to be afraid of now.
一切都结束了。现在没有什么可怕的了。
3）区别与联系：
she was not afraid of dancing with strangers,but she was afraid to dance
with Mr.Green tonight,because she thought him dangerous.
她不害怕和陌生人跳舞（指在舞会上，表示习惯），但是今晚，她不敢和格林跳舞（很可能格林向她发出邀请，因为她觉得格林是个危险人物，不敢跳舞只是今晚这一次）。
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