—I’d like to invite you to my birthday party this evening.—Thanks but I’ll have time I’m

问题补充：

—I’d like to invite you to my birthday party this evening.

—Thanks, but I’ll have time I’m not sure at the moment.

A. while

B. whether

C. if

D. when

答案：

A. while

(答案→)B. whether

C. if

D. when

解析：宾语从句前置用what不用if，目前我不确定是否有时间，故选B。