Question

What do you think made Mary so upset? A.As she lost B.Lost C.Losing D.Because of losing 为什么不选A

What do you think made Mary so upset? A.As she lost B.Lost C.Losing D.Because of losing 为什么不选A？

Answer 1

选C；what 是名词性质的提问词，要回答必须也是“丢失的”名词形式，排除A
B，D.Because of 多余；你把 C.中的 Losing 代入原句就发现是最正确的答案了：Losing made Mary so upset；而Because of losing made Mary so upset不是一个正确的句子。

Answer 2

其实正确答案应该是C。

问的是What不是Why
Why开头的时候才用because回答

Answer 3

如果去掉 "do you think", 并不影响原句含义. 而这个选择就容易许多:
What made Mary so upset?
既然问的是WHAT, 那么一个名词, 名词性词组, 或者动名词就是自然的选择:
C. Losing

Answer 4

as 不能作为一个回答单独使用