Question

See the flags on top of the building? That was          we did this morning

1. A.
   when
2. B.
   which
3. C.
   where
4. D.
   what

Answer 1

D
解析：
主要测试表语从句。句子意思：看到那个建筑顶上的旗了吗？那就是我们今天早晨的杰作啊。分析句子结构可知：句子        we did this morning中动词did缺少宾语，另外该句子还要充当That was 的表语，因此双重作用的引导词只能选择what。