浇口套一般用()热处理方法。
A、淬火
B、回火
C、淬火加低温回火
D、正火
参考答案:C
设直线l过点(-2,0)且与圆x2+y2=1相切,则l的斜率为______.
For all the remaining items the stated dates of delivery are approximate, but () would these dates be exceeded by more than ten days.
A. in no case
B. in any case
C. under any circumstances
D. by all means