The old lady was so pleased with all we had done for her she wrote us a thank-you letter.
A. what; that
B. that; that
C. which; that
D. that; what
网友回答
A. what; that
(答案→)B. that; that
C. which; that
D. that; what
解析：考查定语从句。先行词是all much 等代词时，引导词必须用that；当前面已有其它引导词时，后面引导词只能使用that。根据先行词all可知前面用that，故选B。