be afraid of 后面为什么加to do ,而不是doing?

be afraid of 后面为什么加to do ,而不是doing? be afraid of doing 和 be afraid to do 区别 be afraid to do sth be afraid of doing sth be afaid of doing sth/be afraid that/be afraid to do sth.造句 为什么是be busy doing而不是be busy to do be afraid of doing sth be busy doing sth be glad to do buy s ask sb to do sth be afraid of doing be busy doing be late fo be afraid of doing 与be afraid to do 的区别 be afraid to do sth ,be afraid of doing sth的区别 be afraid to do sth.be afraid of doing sth.的差别? 英语中be afraid of doing be afraid to do 有什么区别? be afraid to do 与 be afraid of doing 有什么区别?