What are ____________ going to do on Sunday? [ ]
A. them
B. they
C. their
答案：B
《煤矿矿井机电设备完好标准》规定：齿轮联轴器齿厚磨损不超过原齿厚的（）。
A．R/4
B．R/2
C．R/8
D．R
