----Why did you go back to the shop?---I left my friend there.A. waitingB. to waitC. wa

问题补充：

----Why did you go back to the shop?

-----I left my friend there.

A. waiting

B. to wait

C. wait

D. waits

答案：

(答案→)A. waiting

B. to wait

C. wait

D. waits

解析：考查现在分词作宾补，leave sb doing 使某人一直做某事，句意：你为什么回商店了，我让我的朋友一直在那等着呢。所以选A。