问题补充：
Tell me when you at the airport, Alice. I’ll go there to meet you if I’m free.
A. arrive
B. would arrive
C. have arrived
D. are arriving
答案：
A. arrive
B. would arrive
C. have arrived
(答案→)D. are arriving
解析：考查短暂性动词的进行时表示将要做某事，when当…时候，由后面的句子可以知道还没有到机场，句意“告诉我你将什么到机场，如果我有空的话，我将去接你”，所以选D
