have been doing sth是什么时态?

have been doing sth have been doing sth是什么时态? 是have difficulty doing sth还是have difficult doing sth? Have/has been 后一定要加doing sth.吗? have(has) been doing sth 造句写翻译 have fun doing sth..这里DOING.是动名词吗. have fun doing sth have fun doing sth. have trouble doing sth have trouble doing sth have sth doing用法? 是have some problem doing sth.还是have some problems doing sth. 到底是have problem doing sth 还是have problems doing sth have been doing sth=have 直接加动词过去分词吗? 英语中have been doing sth和have done 的区别?同上 have problems doing sth与 have trouble doing sthhave problems doing sth .have trouble doing sth.都是对的吗?trouble是可数的吧,怎么不是 troubles? have been doing sth和现在完成时有区别吗?我上课记得老师说现在完成时后面加什么就等于have been doing sth这个延续的句型. have been doing sth 和 have +过去分词 有什么不一样?看见since 之类的词 是应该用哪种形式?如题