—Do you smoke?—No I don’t.It’s two years since I .A. smokedB. have smokedC. has smokedD

问题补充：

—Do you smoke?

—No，I don’t.It’s two years since I .

A. smoked

B. have smoked

C. has smoked

D. don’t smoke

答案：

(答案→)A. smoked

B. have smoked

C. has smoked

D. don’t smoke

解析：since从句中动词若为延续性动词，则意为“自从不……以来”。