would have been doing这个时态怎么用?
有没有have been doing 这个时态?
have been doing是什么时态?
请问have been这个时态一般怎么用
would have been 是什么时态,怎么用,帮忙举几个例子.
How long have you been doing是什么时态的句子?这个时态怎样构成?
have been doing sth是什么时态?
have /has been doing 是什么时态
what have they been doing 是什么时态
have been doing 该怎么用
would have been completed表示什么时态?
what have u been doing的been是什么时态?
英语时态区分have done .have been doing.had done.had been doing.有什么