Question

—Henry doesn’t seem like the same person.
—_________so much in the war has made him more thoughtful

1. A.
   For him to see
2. B.
   His seeing
3. C.
   Having seen
4. D.
   To be seeing

Answer 1

B
很明显答语在结构上缺少主语。To do 与-ing都可充当主语，但 to do充当主语多表示某一具体的动作，且多表将来。故选B。