问题补充：
A：Is that your watch the lost and found case? Please call me
685—6034.
B：Oh, thank you.
A. in, in
B. at, at
C. in, at
D. at, in
答案：
A. in, in
B. at, at
(答案→)C. in, at
D. at, in
解析：此题考查介词的用法。In the lost and found case表示在失物招领处，给某人打电话要用call sb at +电话号码
