My French improved quickly.I'm comfortable _______ French now.(speak)

问题描述:

My French improved quickly.I'm comfortable _______ French now.(speak)
答案是-ing,我写的to do,我要原因!为啥不是to do是doing?

be comfortable doing 里的doing 做伴随状语
我觉得很自在,当我说法语的时候.
speaking 是伴随的状态.
如果用comfortable to do 更强调的是做某个动作很舒服自在