____twice a year, whether it is a car or a bus or a truck, is the rule that every driver must o...

____twice a year, whether it is a car or a bus or a truck, is the rule that every driver must o...

C

本题易误选B。考查动名词的用法，名中whether it is a car…为让步状语从句，is 为系词，故少主语。A、B、C、D中只有C可作主语表被动。