钢轨的轨腰是用来抵抗因受（）而产生的弯曲。
A、拉力
B、压力
C、重力
D、荷载
参考答案：D
带传动中，带的张紧常用的方法有（）和使用张紧轮。
This doubt had been in my mind for some time, but the research still went on some reasons.[ ]
A. to
B. about
C. for
D. in
