问题补充：
Are you still here?You were here half an hour ago. Who for?
A. were you waiting
B. did you wait
C. are you waiting
D. do you wait
答案：
A. were you waiting
B. did you wait
(答案→)C. are you waiting
D. do you wait
解析：根据题意,你还在这儿?你半小时前在这儿.可知下文叙述的是正在发生的事情,故用想现在进行时态,选C,你在等谁?
