汽车上使用的主减速器有（）；（）；（）、轮边主减速器等类型。
参考答案：单级、双级、双速
Lack government support, they had to approach sponsors, organizers, and musicians on their own—at first, she claims, in her country.
A．Lacks
B．Lacked
C．Lacking
D．A lack of
经常储备是企业用于生产（）周转的物资储备。
A、事故
B、正常
