it ( is )six years since he ( began )to learn english

问题描述:

it ( is )six years since he ( began )to learn english
为什么是上面这个用法啊,since不是加完成时的吗,我觉得是was,began

固定句型:it is /has +一段时间+since +句子( 一般过去时)
所以答案是 is