图例“”表示的是[ ]
A.铁路
B.公路
C.洲界
D.国界
答案:C
Shen Xue and Zhao Hongbo won the gold medal for China so we're proud _____ them. [ ]
A. in
B. on
C. of
D. for
当需要传递较大载荷,对中要求较高时,齿轮轴宜采用平键联接。