His English used to be very poor is now excellent.A. whichB. thatC. itD. whom

问题补充：

His English, used to be very poor is now excellent.

A. which

B. that

C. it

D. whom

答案：

(答案→)A. which

B. that

C. it

D. whom

解析：

试题分析:考查定语从句。分析结构可知此处是非限制性定语从句，故排除C、D选项，因为that不引导非限制性定语从句。先行词是English，所以用指代物的关系代词which。正确答案是A。句意：他的英语以前很差，现在却非常棒。