The old lady was so pleased with all we had done for her she wrote us a thank-you letter

问题补充：

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

答案：

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。