问题补充:
The girl often helps her best friend, is not good at English.
A. which
B. who
C. what
D. where
答案:
A. which
(答案→)B. who
C. what
D. where
解析:考查定语从句。根据句子结构可知,此处为非限制性定语从句,先行词为her best friend, 指的是人,故排除A。定语从句中缺少is 的主语,故排除CD。定语从句中没有what的用法,where只能作状语。