33. There was no light in the dormitory last night. So they to the lecture then.A. must

问题补充：

33. There was no light in the dormitory last night. So, they to the lecture then.

A. must have gone

B. should have gone

C. needn’t have gone

D. couldn’t have gone

答案：

(答案→)A. must have gone

B. should have gone

C. needn’t have gone

D. couldn’t have gone

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