2、,主语与谓语是主动关系,谓语改成ing形式,是被动关系改成ed形式。2、People are often killed while___the road. A. cross B. crossing C. to cross D. crossed答:选B该题补充完整就是“Peopleareoftenkilledwhiletheyarecrossing”,they指的就是People,因此可以省略主语和be动词。解析:由while引导的状语从句,可省略主语和助动词be,保留ing分词、ed分词或表语。这样省略的