题目

—John, how did your English exam go? — I thought I _____ , but in fact I came in the top 10% in the class. A. should have failed                         B. might have failed C. couldn’t have failed                      D. mustn’t have failed 答案：B在△ABC中，在△ABC中，∠A，∠B，∠C所对的边分别是a，b，c，若a2=b2+bc+c2，则A=120°120°．