更多"--Is Mrs. White in the office"的相关试题:
[单项选择]—Is this Mr. White's office, Mary
—Yes, ( ).
A. after you
B. it doesn't matter
C. that's all right
D. please yourself
[单项选择]—Is Mrs White in the office
—Yes, _ _____she is on duty, she must be there.
A. since
B. until
C. for
D. if
[填空题]Mr. White and Mrs. White have to____________________(缩短蜜月)because the secretary bothered them with telegrams.
[填空题]
|
CODE NUMBER | SS (9) |
WIDTH | 3.5 (10) wide |
HEIGHT | (11) meters high |
[填空题]
Electromagnetic Energy
White
light seems to be a combination of all colors. The energy that comes from a
source of light is not limited to the kind of energy you can see. Heat is given
off by a flame or an electric light. On a cloudy day it is possible to get a
sunburn even though you feel cool. Visible light and the kind of energy that
produce warmth and sunburn are examples of electromagnetic energy.
The sun is 93 million miles from the earth. Yet we can use energy from
the sun because electromagnetic energy travels through space.
Many other kinds of energy are also types of electromagnetic energy. Radio,
television, and radar signals travel from transmitters to receivers as
low-energy electromagnetic waves, infrared (红外线的) radiation is an
electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of
infrared and visible light have more energy than waves of radio, television, or
radar. Ultraviolet rays (紫外线) and X-rays are electromagnetic waves with even
greater amounts of energy. Infrared radiation is used in cooking food and
heating buildings. Sunlight and electric lights are part of our requirements for
normal living. Ultraviolet radiation is useful in killing certain disease
organisms. X-rays and gamma rays have so mush energy that they travel right
through solid objects. They can be used to detect and treat cancer. X-rays are
used in industry to find hidden cracks in metal, and in medicine to reveal
broken bones.
Usually we use electricity to generate
electromagnetic energy. The source of most of our energy is the sun. Heat from
the sun causes water to evaporate. When the water falls to the earth as rain,
some of it is trapped behind dams and then used to operate electric generators.
Other generators are powered by coal, but the energy stored in coal came from
the sun, too.
Until recently, the source of the tremendous
amount of energy given off by the sun was a puzzle. If the sun depended on
chemical reactions, it would have used up all its energy long ago. Experiments
with electromagnetic radiation led to the theory that mass can be converted into
energy. About forty years after the theory was proposed, nuclear energy was
harnessed (利用) by man. Chemical energy comes from electron (电子) rearrangement.
Nuclear energy comes from a change in the nucleus of an atom. Compared with
chemical reactions, nuclear reactions release millions of times more energy per
pound of fuel. We now believe that the sun’s energy comes from the nuclear
reactions in which hydrogen is changed into helium (氦).
Nuclear
energy is beginning to compete with coal as an economical source of power to
generate electricity. It is also being used to operate engines in large ships.
Scientists continue to seek new and better methods of obtaining and using
energy.Paragraph 3 ______.
A. Nuclear reactions as the lasting source of the sun’s energy
B. The most important source of energy
C. Types of electromagnetic energy
D. The machines used for energy generation
E. Seeking new sources of energy
F. The use of ultraviolet radiation in medicine
[单选题]如何让老版本的Office可以识别Office2007所建立的各种文件()?
A.将文档的扩展名修改为doc、xls、ppt等
B.安装IE7等工具,使其支持XML格式的文件
C.运行老版本Office的升级功能进行升级
D.到微软网站下载MicrosoftOfficeWord、Excel和PowerPoint2007文件格式兼容包
购买搜题卡查看答案
[会员特权] 开通VIP, 查看 全部题目答案
[会员特权] 享免全部广告特权
请选择支付方式
-
微信支付
-
支付宝支付
立即支付
系统将自动为您注册账号
请使用微信扫码支付
请不要关闭本页面,支付完成后请点击【支付完成】按钮
恭喜您,购买搜题卡成功
重要提示:请拍照或截图保存账号密码!
我要搜题网官网:https://www.woyaosouti.com
我已记住账号密码