I failed in the examination last week and I regret hard.A. not to studyB. not studyingC.

问题补充：

I failed in the examination last week and I regret hard.

A. not to study

B. not studying

C. have not studied

D. did not study

答案：

A. not to study

(答案→)B. not studying

C. have not studied

D. did not study

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