had been doing 是什么时态?
had been doing是什么时态
had been doing 是什么时态?
had been doing是什么是时态?
have been doing是什么时态?
had been doing是什么语法?
英语时态区分have done .have been doing.had done.had been doing.有什么
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/has/had加been是什么时态
have been doing sth had 加过去分词 have has 加过去分词 分别是什么时态?求什么区别?最
what have u been doing的been是什么时态?