UPS不间断电源与正常电源之间必须采用防止其并列运行的措施,目的是防止( )。 A

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问题:

UPS不间断电源与正常电源之间必须采用防止其并列运行的措施,目的是防止( )。

A.系统电压下降
B.系统频率下降
C.系统形成环流而烧损
D.两个电源同时作用于系统

考点:注册电气工程师供配电专业注册电气工程师专业考试(供配电专业)
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阅读理解。

     The first telephone cards, produced in 1976, were Italian. Five years later the first British card appeared,

and now you can buy cards in more than a hundred countries. People usually start collecting cards because

they are small and light and you do not need much space for them. It is also a cheap hobby for beginners,

although for some people it becomes a serious business. In Paris, for example, there is a market where you

can only buy telephone cards, and some cards cost up to £4,000. The first Japanese card has a value of

about £28,000. Most people only see cards with prices like these in their collectors' magazine.

1. When were the first Italian telephone cards produced?  

    _______________________________________________ 

2. How many countries can produce telephone cards now?

    _______________________________________________    

3. Where can we find a market to buy telephone cards? 

    _______________________________________________    

4. What is the price of the first Japanese telephone card? 

    _______________________________________________

5. In which magazine do most people see cards with prices? 

   _______________________________________________

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胞痹

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胆总管结石合并急性梗阻性化脓性胆管炎时发生的并发症不包括

A.感染性休克
B.急性胰腺炎
C.肝脓肿
D.结石压迫门静脉引起肝外型门静脉高压症
E.胆道出血

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扩散是由于系统中各部分()不同而引起的自发过程。

题型:多项选择题

推进扣合内钳时,要面向井口钻具,(),双臂用力将吊钳推近立柱,然后右手用力使钳头沿接头本体外缘推进并与钳框自动扣合。

A.左腿弓,右腿蹬

B.右腿弓,左腿蹬

C.双腿弓

D.两腿蹬

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