The reason why she came here late this morning was she had to look after her sick daughter

问题补充：

The reason why she came here late this morning was she had to look after her sick daughter.

A. why

B. because

C. that

D. because of

答案：

A. why

B. because

(答案→)C. that

D. because of

解析：考查固定句型。The reason is that…原因是…;that后面接表语从句。不能说the reason is because/why….because of后面不能接句子。故C正确。