when 后面直接+doing 或者+ did 是什么语法现象?
举个例子
when doing my homework, i found him coming in.
这里是一个时间状语
doing 表示主动态,did 是被动态,如:
when attacked by the enemy ,he didn't do anything in return
举个例子
when doing my homework, i found him coming in.
这里是一个时间状语
doing 表示主动态,did 是被动态,如:
when attacked by the enemy ,he didn't do anything in return