Question

—Henry doesn’t seem to be what he was.

—No. so many terrible things in the war has made him more thoughtful.

1. A.
   Seen
2. B.
   His having seen
3. C.
   Having seen
4. D.
   To have seen

Answer 1

B
句子的谓语是has made，“看到战争中如此多可怕的事”是说明已发生的事实，对现在有影响，故应用动名词的完成式作主语。