is necessary for everyone to obey the traffic rules.A. ThatB. ThisC. WhatD. It

问题补充：

is necessary for everyone to obey the traffic rules.

A. That

B. This

C. What

D. It

答案：

A. That

B. This

C. What

(答案→)D. It

解析：本题的含义是对于每个人而言服从交通规则是必要的，本题运用了形式主义it，真正的主语位于句尾用动词不定式，故本题选D。