You must look around when you go _____ the street.[ ]
A. cross
B. past
C. on
D. across
答案:D
三个互不相等的实数a,b,c成等比数列,且满足a+b+c=2,则实数b的取值范围为______.
电机悬挂装置检修时,先进行(),松开刚性悬挂体与电机连接螺栓,取下刚性悬挂装置送到检修处所。