杆件内力矢量沿其轴线的分量，称为（）。
A.轴力
B.剪力
C.扭矩
D.弯矩
参考答案：A
-------- The window is dirty.
--------- I know. It __________ for weeks.
A．hasn’t cleaned
B．didn’t clean
C．wasn’t cleaned
D．hasn’t been cleaned
呕血的病史采集要点
