在转速负反馈直流调速系统中,当负载增加以后转速下降,可通过负反馈环节的调节作用使转速

题型:单项选择题

问题:

在转速负反馈直流调速系统中,当负载增加以后转速下降,可通过负反馈环节的调节作用使转速有所回升,系统调节前后,电动机电枢电压将()。

A、增大

B、减小

C、不变

D、不能确定

考点:高级维修电工高级维修电工题库
题型:单项选择题

下列尺规作图的语句正确的是( )

A.延长射线AB到点C

B.延长直线AB到点C

C.延长线段AB到点C,使BC=AB

D.延长线段AB到点C,使AC=BC

题型:单项选择题

现有下列仪器,其中在制取二氧化碳时不需用到的是(  )

A..锥形瓶

B..酒精灯

C.导管

D..集气瓶

题型:单项选择题

某企业2011年购销情况如下:年初存货结存20万千克,单价8元,9月购进80万千克,单价6元,12月销售存货40万千克,单价10元。假设企业存货方法可以选择加权平均法和先进先出法中的一种,不存在纳税调整事项,企业所得税税率为25%,则从所得税的角度考虑,企业适合采用加权平均法。( )

题型:单项选择题

斯大林认为,()是政策主体针对运动的来潮与退潮而采取的行动路线。

A.战术

B.策略

C.战略

D.政策

题型:单项选择题

When you want to go shopping and decide how much money you can spend for new clothes, think about the kind of clothes you really need. Then look for those clothes on sale. There are labels(标签) inside all new clothes. The labels tell you how to take care of your clothes. The label for a shirt may tell you to wash it in warm water. A sweater label may tell you to wash by washing in cold water. The label on a coat may say "dry clean only". Washing may ruin(毁坏) this coat. If you do as the directions say on the label, you can keep your clothes looking their best.
Many clothes today must be dry-cleaned. Dry cleaning is expensive. When buying new clothes, check to see if they will need to be dry-cleaned. You will save money if you buy clothes that can be washed. You can save money if you buy clothes that are well-made. Well-made clothes last longer. They look good even after they have been washed many times. Clothes that cost more money are not always better made. They do not always fit better. Sometimes less expensive clothes look and fit better than more expensive clothes.

Cheaper clothes can sometimes fit you better,
[A] Right. [B] Wrong. [C] Doesn’t say.

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