---How did you do in the test yesterday?---Not so well. I much better but I misread th

问题补充：

---How did you do in the test yesterday?

-----Not so well. I much better but I misread the directions for writing。

A. will have done

B. could have done

C. must have done

D. may have done

答案：

A. will have done

(答案→)B. could have done

C. must have done

D. may have done

解析：考查虚拟语气。ACD三项都不能用来表示虚拟语气。句意：—在昨天的考试中你表现怎么样?—不是很好。我本可以做得更好，但是我看错了写作的要求。Could have done本可以做，实际上却未做。故B正确。