His English a lot since he took the course.A. improvedB. was improvedC. has improvedD. ha

问题补充：

His English a lot since he took the course.

A. improved

B. was improved

C. has improved

D. has been improved

答案：

A. improved

B. was improved

(答案→)C. has improved

D. has been improved

解析：句意：自从他上了这个课程，他的英语提高了很多。since引导的时间状语，主句要用现在完成时，his English是单数形式，所以用助动词has，故选C。