—How did you do on the test?—Not so well. I much better but I misread the directions for

问题补充：

—How did you do on the test?

—Not so well. I much better, but I misread the directions for Part One.

A. could

B. could have done

C. must have done

D. should do

答案：

A. could

(答案→)B. could have done

C. must have done

D. should do

解析：

这题考查情态动词的虚拟语气，could have done“本可以做…却没有”，句意是：--你考试怎样？--不是很好，我本可以更好，但是我误解了第一部分的说明。