twice a year whether it is a car or a bus or a truck is the rule that every driver must ob

问题补充：

twice a year，whether it is a car or a bus or a truck，is the rule that every driver must obey in this city.

A. Examining

B. Examined

C. Being examined

D. Having been examined

答案：

A. Examining

B. Examined

(答案→)C. Being examined

D. Having been examined

解析：

句中缺少的是主语，分词不作主语，故排除A、B项；从整个句子意思来看examine需要用被动式且用其一般式即可。