He promised his old friend during his stay in Tianjin.A. seeB. seeingC. sawD. to see

问题补充：

He promised his old friend during his stay in Tianjin.

A. see

B. seeing

C. saw

D. to see

答案：

A. see

B. seeing

C. saw

(答案→)D. to see

解析：句意：在他在天津期间他承诺去看他的老朋友。动词不定式做宾语表示具体的将要发生的动作，结合语境可知选D。