you work hard you won’t solve this problem.A. EvenB. AsC. UnlessD. Since

问题补充：

you work hard, you won’t solve this problem.

A. Even

B. As

C. Unless

D. Since

答案：

A. Even

B. As

(答案→)C. Unless

D. Since

解析：Even即使，甚至；As因为，由于；Unless除非……否则，如果不；Since

自从，因为。句意：除非你努力学习，否则你不能解决这道题。所以选C。