题目

We __________ so tired. We've only been to a party. A. mustn't have felt            B. wouldn't have felt C. shouldn't have felt          D. couldn't have felt 答案：C 解析: 本题是情态动词的考查。should（not）后接动词的完成式表示“本来（不）应该做但实际上做了”的含义。如图：∠CAD是△ABC的一个外角，且∠CAD=2∠B，试说明AB=AC．