- Have you solved your problem?---Ive kept on thinking about that matter but I have

问题补充：

--- Have you solved your problem?

---Ive kept on thinking about that matter , but I have no idea yet now.

A. at times

B. some time

C. at a time

D. all the time

答案：

A. at times

B. some time

C. at a time

(答案→)D. all the time

解析：at times有时，偶尔；some time一些时间，在某时；at a time一次，每次； all the time始终，一直。句意：你解决你的问题了吗？——我一直在思考那个问题，但是现在我还没有主意。结合语境可知选D。