Are they still doing the experiment? They're supposedit by the end of last class.A. finish

问题补充：

Are they still doing the experiment? They e supposedit by the end of last class.

A. finish

B. finished

C. to finish

D. to have finished

答案：

A. finish

B. finished

C. to finish

(答案→)D. to have finished

解析：可联系答.案.网客服索取。