问题补充:
twice a year,whether it is a car or a truck,is the rule that every driver must obey in this city.
A. Examining
B. Examined
C. Having examined
D. Being examined
答案:
A. Examining
B. Examined
C. Having examined
(答案→)D. Being examined
解析:此题考查非谓语动词。Being examined twice a year系动名词短语的被动形式作了句子的主语。