---You could have asked your brother for help. He is good at math.
---Yes. A whole day .
A. will waste
B. had wasted
C. was wasted
D. would be wasted
网友回答
A. will waste
B. had wasted
(答案→)C. was wasted
D. would be wasted
解析：could have asked是虚拟语气，表示“本可以做……”，因此答语应用过去时与上句呼应。