in the dark his head hit against a tree.A. WalkingB. He was walkingC. WalkedD. When he

问题补充：

in the dark, his head hit against a tree.

A. Walking

B. He was walking

C. Walked

D. When he was walking

答案：

A. Walking

B. He was walking

C. Walked

(答案→)D. When he was walking

解析：考查从句。当分词做状语时，和主句的主语有一定的逻辑关系。主句的主语是his head和walk无逻辑上的关系，一个句子中也不能有两个主语。故选D，当他正走在黑暗中时，他的头撞到了树上。