问题补充:
---Please come here again.
-----I will surely you when I come to your city someday.
A. drop in at
B. drop in
C. drop on
D. drop in on
答案:
A. drop in at
B. drop in
C. drop on
(答案→)D. drop in on
解析:drop in on +人意为:顺便走访某人; drop in at+地方意思是:顺便走访某地方。