It ___ten years since i taught in the schoolA is B was C has D is

It ___ten years since i taught in the schoolA is B was C has D is
It ___ten years since i taught in the school
A is B was C has D is

It ___ten years since i taught in the schoolA is B was C has D is
D
It is + 一段时间 since .这是固定句型,“做某事已经...时间了”
It is ...也可写作It has been ...

D is
从我在学校教书到现在已经10年了