—Mr. Li let’s go fishing this weekend with Lao Wang shall we?—I’d love to but nobody k

问题补充：

—Mr. Li, let’s go fishing this weekend with Lao Wang, shall we?

—I’d love to, but nobody knows if he free then.

A. will

B. is

C. will be

D. has been

答案：

A. will

B. is

(答案→)C. will be

D. has been

解析：在if 引导的宾语从句中，从句的时态，要根据本来的时态决定，故选C