问题补充：
Im afraid I have to go now, for my parents outside.
A. had waited
B. have waited
C. are waiting
D. were waiting
答案：
A. had waited
B. have waited
(答案→)C. are waiting
D. were waiting
解析：句意：现在我想我必须走了，因为我的父母正在外面等着。分析：现在要走，说明父母的动作也正在进行，因此为现在进行时。故选 C
