一道英语动宾结构省略的问题You should always rememeber to knock the door when_______(enter)the room.用enter的正确形式填空,并说明理由.

问题描述:

一道英语动宾结构省略的问题
You should always rememeber to knock the door when_______(enter)the room.
用enter的正确形式填空,并说明理由.

entering主动语态

用entering,因为entering the room=when you enter the room的省略形式的表达

entering the room=when you enter the room的省略形式的表达.