单位切削力
参考答案：
单位切削面积上的平均切削力，亦即切削力与切削面积之比。
twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city．
A．Examining
B．Examined
C．Being examined
D．Having been examined
汽车式起重机作业中，禁止下列哪种操作。（）
A.回转
B.调整支腿
C.起升
D.向上变幅
