how long have you been studying为什么后面要加ing

此为现在完成进行时,表示从过去某时开始一直持续到现在的动作,并且还将持续下去
基本表达式：
I/ we/ you/ they have been doing sth.
he/ she/ it has been doing sth.
原句表示：你到目前为止学了多久的英文（学英语的行为还会持续）
i have been studied since ...这个句子是错误的,have been studied 是过去完成时的被动语态
we have been married for ..
这个句子里面have been married表状态,是现在完成时,而have been studied中study为行为动词,一般没有been studied一说