I must be off now. My friends outside.A. waitB. have waitedC. are waitingD. were waiting

问题补充：

I must be off now. My friends outside.

A. wait

B. have waited

C. are waiting

D. were waiting

答案：

A. wait

B. have waited

(答案→)C. are waiting

D. were waiting

解析：考查时态。根据上文的must be说明是对现在的情况进行说明，因为“must+动词原形”说明对现在的情况进行推测。故C正确。句意：我现在必须得走了，我的朋友在外面等我。