--Why don't you try your best to get on the bus?—I tried to but I could it started movi

问题补充：

--Why don you try your best to get on the bus?—I tried to , but I could, it started moving.

A. until

B. when

C. before

D. after

答案：

A. until

B. when

(答案→)C. before

D. after

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