it takes him two hours to finish doing his homework为啥用doing?不是it takes sb.sometime to do sth
问题描述：
it takes him two hours to finish doing his homework为啥用doing?不是it takes sb.sometime to do sth
答
“it takes him two hours to finish ”用的是it takes sb.sometime to do sth
而finish后面用动词ing形式 finish doing sth