将钢加热到临界温度以上,保温一段时间,然后水、盐水或油中急速冷却,称为()。A、正火 发布时间:2019-09-08 03:09 │ 来源:www.tikuol.com 题型:单项选择题 问题: 将钢加热到临界温度以上,保温一段时间,然后水、盐水或油中急速冷却,称为()。A、正火B、淬火C、回火
题型:单项选择题 Which of the following is least likely to be considered a reason for the existence of a natural monopoly()A. Firms that can maximize profit when price equals marginal cost.B. Firms that have significant economies of scale.C. Firms that have significant economies of scope. 查看答案