由于二极管通电时电阻很小,可以看成短路,相当于开关();二极管截止时反向电阻很大可以

题型:填空题

问题:

由于二极管通电时电阻很小,可以看成短路,相当于开关();二极管截止时反向电阻很大可以看成是开路,相当于开关()。这就是二极管的开关特性。

考点:矿井机电维修工矿井机电维修工题库
题型:填空题

阅读理解。

     Drinking water is good for your health. There are some scientific ways of drinking water.

     1. It is the best medicine to drink two glasses of water in the morning.

     2. Drink clean water.

     3. Drink the water that has not been boiled.

     Many people think boiled water is safe and good to people's health. In fact, it is not true. The boiling point

of water is 100℃. By boiling it, most bacteria in water can be killed. In the past, the water was less polluted,

so boiling was a good way to make clean water. But heavy metals and other dangerous things in today's water

are much more terrible than bacteria. Boiling doesn't fix that problem. And boiling water may give us more of

die dangerous things in our glass.

     4. Never use soft drinks to take the place of water.

     5. Water is also needed in winter.

     6. Drink water in the right time.

     1) After getting up in the morning, you have less water in your body, because you weren't drinking for the

whole night. So you should drink some water to keep your health after getting up in the morning. That can

prevent high blood pressure, cerebral hemorrhages (脑湓血), and so on.

     2) Drinking water at about 10 am helps your body keep enough water.

     3) Drinking water at about 3 pm can clean out the wastes in your body.

     4) About eight o'clock in die evening is the best time to drink water. Your blood gets thicker when you sleep.

Water will make your blood less thick.

     Besides, we should drink 2L of water every day. Water is so important for our life. We should drink water

often.

1. According to the passage. in the meaning is die best _____.

A. drinking some hot soup, medicine

B. drinking some porridge, breakfast

C. drinking dome water, medicine

2. _____ can prevent high blood pressure, cerebral hemorrhages and so on.

A. Drinking some water after getting up in the morning

B. Drinking some water before going to bed

C. Drinking some milk before going to bed

3. At about 3 pm, drinking water can clean the _____ in your body.

A. oil

B. food

C. wastes

4. From the passage, we can see the best time to drink water is _____.

A. about eight o'clock in the morning

B. about eight o'clock in the evening

C. before supper

5. The best title (标题) to this passage is _____.

A. Drink clean water

B. Don't drink the boiled water

C. Scientific water drinking

题型:填空题

哪项属于正反馈

A.腱反射

B.减压反射

C.排尿反射

D.肺牵张反射

E.对侧伸肌反射

题型:填空题

世界是物质的,物质又是多样的。

从下列物质A. 氧气 B.干冰 C. 一氧化碳 D.碱式碳酸铜中,请选择恰当的物质名称前的字母序号填写在横线上。

(1)空气中含量较多性质比较活泼的气体是_______________;

(2)能用于人工降雨和制造舞台云雾的是_____________;

(3)空气污染物之一,常引起煤气中毒的气体是_____________;

(4)铜器件锈蚀形成的绿色粉末,俗称铜绿的物质____________。

题型:填空题

甲公司与乙公司草签了一份电冰箱购销合同。合同约定:甲公司向乙公司购买电冰箱100台,每台单价3000元,总货款为30万元。为了保证甲公司履行合同,甲公司预付款10万元。如果甲公司退货,违约金比例为总货款的30%,如果电冰箱价格上涨,乙公司有单方面解除合同的权利。
请回答以下问题:

下列对合同预付款、违约金的说法中,正确的是( )。

A.预付款的比例不符合法律规定

B.违约金的比例不符合法律规定

C.违约金的比例符合法律规定

D.预付款作为合同的担保方式,力度比定金小

题型:填空题

《史记》是中国古代史书中“信史”的典范,简单谈谈你对此的认识。

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