（）是指踏面在钢轨上接触的轴向长度。
参考答案：搭载量
I promised to get there before 5 o’clock, but now the rain is pouring down. They _______ for me impatiently.
A．may wait
B．ought to wait
C．could wait
D．must be waiting
胸椎的特征： ( )
A．椎体和横突有肋凹
B．横突上有横突孔
C．棘突水平、末端分叉
D．椎体最小
