何谓中性点位移?
参考答案:
在三相电路星形连接的供电系统中,电源的中性点与负载的中性点之间产生的电位差,称为中性点位移。
对考生文件夹下的数据库“员工管理”中的“员工信息”表和“职称信息”表完成如下操作: ①为表“职称信息”增加两个字段“人数”和“明年人数”,字段类型均为整型。 ②编写命令程序myp,查询职工中拥有每种职称的人数,并将其填入表“职称”的“人数”字段中,根据职称表中的“人数”和“增加百分比”,计算“明年人数”的值,如果增加的人数不足一个,则不增加。 ③运行该程序。
词汇。
1. You can buy some _____ (生活必需品) in thesupermarket.
2. In the modern world,_____ (广告) is everywhere!
3. The doctor asked my father to_____ (放弃) smoking to keep healthy.
4.Li Hong is_____ (害怕的)of staying alone at home in the evening.
5. I like this_____ (杂志). There are many photos in it.
6. I have no_____ (经验)in selling products.
7. Lucy and Lily_____ (轮流)to clean their rooms.
8. I lost the book I borrowed from the library. I have to_____ (为…付款) it.