问题补充：
You can come here to ask me if you have any questions.
A. at one time
B. at a time
C. at any time
D. all the time
答案：
A. at one time
B. at a time
(答案→)C. at any time
D. all the time
解析：考查短语辨析，at one time一度，曾经，at a time 一次，每次，at any time 在任何时候，all the time 一直，句意：如果你有问题的话任何时候你可以过来问我。故选C。
