How long have you been doing是什么时态的句子?这个时态怎样构成?

How long have you been doing是什么时态的句子?这个时态怎样构成? 一句话的时态问题How long have you been stay here?请问这句话是什么时态,并且说出这种时态 have been doing是什么时态? Have you ever been to shanghai?这个句子是什么时态 what have u been doing的been是什么时态? how long have you been like this?为什么用完成时态?请类似的举例 有没有have been doing 这个时态? 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是什么时态? have+been是什么时态