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是什么时态 had been doing是什么是时态? 英语时态区分have done .have been doing.had done.had been doing.有什么区别. what have they been doing 是什么时态 have been doing sth是什么时态? have/has/had加been是什么时态 what have u been doing的been是什么时态? had been doing是什么时态,从过去持续的现在?还是过去的过去?还是别的什么 had been什么时态 have been doing,had been doing,will have been down是什么 had had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?最好有例句、、 had had been taken 是什么时态那解释一下两个had分别是什么作用 i wish you had been more interested in culture.为什么用had been 是什么时态? had been doing是什么语法?举个例子~有have/has been doing的说法吗? How long have you been doing是什么时态的句子?这个时态怎样构成?