客运周期量
参考答案：是指统计期内汽车运输过程中所完成的客运量（千人）与运距的乘积。
The trees ______ in the storm have been moved off the road.
[ ]
A. being blown down
B. blown down
C. blowing down
D to blow down
焊接变形的基本形式有哪些？防止和减小焊接变形的措施有哪些？当焊接变形产生后应如何去矫正？
