It’s more than 8 years since I a teacher.A. becomeB. has becomeC. becameD. becomes

问题补充：

It’s more than 8 years since I a teacher.

A. become

B. has become

C. became

D. becomes

答案：

A. become

B. has become

(答案→)C. became

D. becomes

解析：句意：自从我成为一名老师以来，已经八年多了。Since后多接一个时间点，表示自……以来，结合语境可知下文从句描述的是过去某时的动作，故用一般过去时态，选C。