We dont know to pay a visit to the old town.A. whetherB. ifC. thatD. which

问题补充：

We don know to pay a visit to the old town.

A. whether

B. if

C. that

D. which

答案：

(答案→)A. whether

B. if

C. that

D. which

解析：宾语从句中，动词不定式前用whether而不用if。