零件渗透后一般需经（）处理，才能达到表面硬而耐磨的目的。
A、淬火+低温回火
B、表面淬火+中温回火
C、调质
参考答案：C
In order to support the big family, he worked so hard that___________ he made himself ill.
A．occasionally
B．purposefully
C．normally
D．eventually
( )是指监理单位的监理活动收入扣除直接成本、间接成本和各种税金之后的余额。
A．购货款 B．利润 C．总成本 D．投资额
