It's over two years since I have become a teacher改错

问题描述:

It's over two years since I have become a teacher改错

It's over two years since I became a teacher.
since 引导的时间状语从句中不能用现在完成时,而要用一般现在时.一般现在时?became是一般现在时吗?手误,是一般过去时。不好意思!