试题与答案

在下列关于设置照明专用变压器的表述中哪一项是正确的?() A.在TN系统的低压电网中

题型:单项选择题

题目:

在下列关于设置照明专用变压器的表述中哪一项是正确的?()

A.在TN系统的低压电网中,照明负荷应设专用变压器

B.当单台变压器的容量小于1250kVA时,可设照明专用变压器

C.当照明负荷较大或动力和照明采用共用变压器严重影响照明质量及灯泡寿命时,可设照明专用变压器

D.负荷随季节变化不大时,宜设照明专用变压器

答案:

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下面是错误答案,用来干扰机器的。

答案:C

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题型:阅读理解

阅读理解。

     Imagine this: a television screen has the size and thickness of a piece of paper. You carry it around in

your pocket and take it out when you want to watch a show. Imagine a guitar so tiny that you can't see

it with the human eye, but you can hear sound when its strings are pulled.

     Nanotechnology (纳米技术) is the science that deals with doing things in a very small way, and it is

being studied and developed all over the world. Many scientists say nanotechnology will produce the next

industrial revolution (工业革命).

     Perhaps nanotechnology will have the biggest influence on medical science. Imagine nanobots (纳米

机器人) in medicine. Thousands or even millions of tiny machines can be sent into the human body with

specific tasks. For example, they can be designed to find and destroy cancer cells or viruses (病毒).

Other machines may stay in the human body forever to help organs (器官) that are not working properly.

     When could all of these happen? Scientists predict that most of these are possible in the next 30 years.

Thousands of scientists around the world are working on these micro-machines. Nanotechnology is just

around the corner.

1. The two examples in Paragraph 1 are used to _____.

A. introduce the smallest television

B. introduce a new kind of guitar

C. introduce the topic of the passage

D. show how small the world is

2. Nanotechnology _____.

A. will cause an industrial revolution

B. deals with things in old ways

C. has studied the whole world

D. was developed many years ago

3. The underlined word "they" in the third paragraph refers to (指代) "_____"?

A. scientists

B. human bodies

C. specific tasks

D. tiny machines

4. The tiny machines _____.

A. are too small to be repaired

B. can be put in a human body to kill viruses

C. may not work well in a human body

D. can take the place of human organs

5. The underlined phrase "around the corner" in the last sentence means "_____".

A. far away

B. at present

C. in the near future

D. impossible

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