It is ten months since he a doctor. A. becomesB. becameC. has becomeD. had become

问题补充：

It is ten months since he a doctor.

A. becomes

B. became

C. has become

D. had become

答案：

A. becomes

(答案→)B. became

C. has become

D. had become

解析：考查时态。本题是一个固定句式。Since自从…；后面的句子使用一般过去时，前面的主句使用现在完成时或者一般现在时；本题我们的it is可以换成it has been…；句意：自从他成为一名医生到现在已经了。说明他是前做医生的。故B正确。