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
网友回答
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。