在立式车床上车削内外圆时，立刀架或侧刀架行程应由上往下切削，使切削力始终压向工件与工作台贴合，这样可以减小工件的装夹变形。( )
参考答案：对
其呼吸困难的类型属于
A．吸气性
B．呼气性
C．混合性
D．血源性
E．心源性
Why will the speaker make the call().
A.Because he will let the other person know about the assignment
B.Because he needs to talk to somebody.
C.Because he can’t talk about the assignment now.
D.Because he wants to know about the assignment.
