阅读理解 Some radio signals are reflected when they meet solid objects; for example, television signals are reflected when they meet walls and houses, or when they meet an aircraft in the sky. The pictur 题目和参考答案——青夏教育精英家教网—

阅读理解

　　Some radio signals are reflected when they meet solid objects; for example, television signals are reflected when they meet walls and houses, or when they meet an aircraft in the sky. The picture is not clear when the signals are reflected like this. When a plane is flying near the house, the picture on the television screen sometimes dances about in a very troublesome (讨厌的) way.

　　These reflections, which led Watt to the science of radar, are now used a great deal. Radar instruments (仪器) can show the direction and the distance of aircraft. The signals are reflected only when the instrument points at the aircraft; this shows the direction. How do we find the distance?

　　Electromagnetic (电磁的) waves travel at a speed of 186, 300 miles per second. We know when the signal is sent out; we notice when it comes back. The signal takes a small fraction (小部分) of a second to go and return, but this time is known. So we know the distance from the ground to the plane.

　　Radar is very important to ships on the sea. In most big ships, a radar instrument is always watching the sea on all sides. It transmits (发射) a beam [(光线的)束] of radar waves and turns round all the time. If any other ship reflects the signal, a white spot is shown on a screen on board.

　　Big aircraft also use radar. The instrument finds other aircraft in the sky. A man’s eye is not good enough to do this because it cannot see far enough, but the radar beam can see for many miles.

　　A big plane flies at about 600 miles per hour, which is ten miles per minute. If two jet planes are flying towards each other, they are twenty miles nearer together after a minute has passed. This is dangerous unless the pilots know the facts and the radar instruments show them the facts.

1．What is necessary for the reflection of a radio signal is the ________ of an object.

[　　]

A．hardness

B．location

C．size

D．distance

2．It can be inferred that Watt got the idea of his invention of radar from ________.

[　　]

A．the science of radar

B．shooting stars

C．the reflection of a radio signal

D．none of these

3．By the use of radar we can know ________.

[　　]

A．the distance of a solid object far away

B．everything we want to see

C．the direction of a far-away object

D．Both A and C.

4．The speed of electromagnetic waves is ________.

[　　]

A．600 miles per second

B．more than 180 thousand miles per second

C．about 18 thousand miles per second

D．none of the above

5．When a radar instrumant spots something, we can see, according to the author, ________ on its screen.

[　　]

A．some electromagnetic waves

B．a beam of light

C．a white spot

D．some numbers

答案：A;C;D;B;C

练习册系列答案

年级	高中课程	年级	初中课程
高一	高一免费课程推荐！	初一	初一免费课程推荐！
高二	高二免费课程推荐！	初二	初二免费课程推荐！
高三	高三免费课程推荐！	初三	初三免费课程推荐！
更多初中、高中辅导课程推荐,点击进入>>

相关习题

科目：高中英语 来源：高中课程新学案　高中三年级、英语 题型：050

阅读理解。

　　Many Americans are turning to Japan, they think, a country of high academic achievement and economic success, for possible answers．However, the answers provided by Japanese preschools are not the ones Americans expected to find．In most Japanese preschools, surprisingly little emphasis is put on academic instruction．In one survey, 300 Japanese and 210 American preschool teachers, child development specialists, and parents were asked about various aspects of early childhood education．Only 2 percent of the Japanese respondents(答问卷者)listed“to give children a good start academically”as one of their top three reasons for a society to have preschools．In contrast, over half the American respondents chose this as one of their top three choices．To prepare children for successful careers in first grade and beyond, Japanese schools do not teach reading, writing, and mathematics, but rather skills such as determination, concentration, and the ability to work as a member of a group．The huge majority of young Japanese children are taught to read at home by their parents．

　　Like in America, there is diversity(多样性)in Japanese early childhood education．Some Japanese kindergartens have specific aims, such as early musical training or potential development．In large cities, some kindergartens are attached to universities that have elementary and secondary schools．Some Japanese parents believe that if their young children attend a university-based program, it will increase the children's chances of eventually being admitted to top-rated schools and universities．Several more progressive programs have introduced free play as a way out for the heavy intellectualizing in some Japanese kindergartens．

(1)

We learn from the first paragraph that many Americans believe ________．
[　　]
A．	Japanese parents are more involved in preschool education than American parents
B．	Japan's economic success is a result of its scientific achievements
C．	Japanese preschool education emphasizes academic instruction
D．	Japan's higher education is superior to theirs

(2)

In Japan's preschool education, the focus is on ________．
[　　]
A．	preparing children academically
B．	developing children's artistic interests
C．	developing children's potential
D．	shaping children's character

(3)

Why do some Japanese parents send their children to university-based kindergartens?
[　　]
A．	They can have better chances of getting a first-rate education．
B．	They can make more group experience grow there．
C．	They can be individually oriented when they grow up．
D．	They can do better in their future studies．

(4)

Free play has been introduced in some Japanese kindergartens in order to ________．
[　　]
A．	broaden children's knowledge
B．	lighten children's study load
C．	train children's creativity
D．	enrich children's experience

(5)

Which of the following statements is true?
[　　]
A．	Most of the Japanese preschools pay much attention to academic instructions．
B．	Very few Japanese respondents don't agree to give children a start academically．
C．	In Japan it is common for parents to teach their children at home．
D．	American respondents don't agree to give children a start academically．

查看答案和解析>>

科目：高中英语 来源：黄冈重点作业　高一英语（下） 题型：050

阅读理解：

Meaningful Colours

　　Mary did not understand such sentences as “She is blue Today”, “You are yellow”,“He has a green thumb (大拇指)”,“He has told a little white lie”and so on. And she went to her teacher for help.

　　Mary : Mrs Smith, there is a colour in each of these sentences. What do they mean?

　　Mrs Smith : In everyday English, Mary, blue sometimes means sad. Yellowafraid. A person with a green thumbgrows plants well. And a white lie is not a bad one.

　　Mary : Would you give me an example for “a white lie”?

　　Mrs Smith: Certainly. Now I give you some cake. In fact you don't like it, but you won't say it. Instead, you say, “No, thanks. I'm not hungry.”That's a white lie.

　　Mary: Oh, I see. Thank you very much.

1．Sometimes “yellow”means “afraid” in ________ English.

[　　]

A．correct

B．usual

C．spoken

D．written

2．The farmer doesn't have a green thumb, that is to say ________.

[　　]

A．he is not good at planting

B．all his plants grow well

C．he should have a green thumb

D．he can't grow well like plants

3．John is ________ go to out alone at night. He's yellow!

[　　]

A．afraid

B．brave

C．fear

D．frightening

4．Mary didn't want to tell me ________ of her serious illness.

[　　]She told me a white lie.

A．the cause

B．the reason

C．the truth

D．the news

5．If you fail to pass the exams, you'll be ________.

[　　]

A．yellow

B．blue

C．white

D．green

查看答案和解析>>

科目：高中英语 来源：黄冈重点作业　高一英语（下） 题型：050

阅读理解：

　　In the United States, boys and girls start school when they are five years old. In some states they must stay in school until they are sixteen. Most students are seventeen or eighteen years old when they graduate from secondary school. Another name for secondary school is high school.

　　Most children go to public elementary (初小) and secondary school. The parents of public school pupils do not have to pay directly (直接地) for their children's education because tax (税)money supports the public schools. If a child attends a private (私立) school, his parents pay the school for the child's education.

　　Today about half of the high school graduates go on to colleges and universities. Some colleges and universities receive tax money from the governments. A student at a state university does not have to pay very much if his parents live in that state. Private colleges and universities are expensive. However, almost half of the colleges students in the United States work while they are studying. When a student's family isn't rich, he has to earn money for part of his college expenses.

1．In the United States, children can start school ________.

[　　]

A．at any time

B．when they are old enough

C．at the age of seven

D．when they are five

2．________ between secondary school and high school.

[　　]

A．There is no difference

B．There is little difference

C．There is some difference

D．There is much difference

3．Most parents in the US ________ for their children's education.

[　　]

A．pay the school

B．pay nothing

C．pay little to the school

D．don't pay the school

4．Some students at a state university don't have to pay much money for their higher education because ________.

[　　]

A．tax money supports some colleges and universities

B．their parents live in that state

C．they earn money

D．their family are not rich

5．Students from poor families ________.

[　　]

A．stop studying after secondary school

B．don't go on to colleges and universities

C．have to work to support their families

D．earn money for part of their college expenses

查看答案和解析>>

科目：高中英语 来源：101网校同步练习　高二英语　人民教育出版社(新课标A　2002-3年初审通过) 人教版 题型：050

阅读理解：

　　Suppose we built a robot(机器人)to explore the planet Mars．We provide the robot with seeing detectors(探测器)to keep it away from danger．It is powered entirely by the sun．Should we program the robot to be equally active at all times?No．The robot would be using up energy at a time when it was not receiving any．So we would probably program it to stop its activity at night and to wake up at dawn the next morning．

　　According to the evolutionary(进化的)theory of sleep, evolution equipped us with a regular pattern of sleeping and waking for the same reason．The theory does not deny(否认)that sleep provides some important restorative functions(恢复功能)．It merely says that evolution has programmed us to perform those functions at a time when activity would be inefficient and possibly dangerous．However, sleep protects us only from the sort of trouble we might walk into; it does not protect us from trouble that comes looking for us．So we sleep well when we are in a familiar, safe place, but we sleep lightly, if at all, when we fear that bears will nose into the tent．

　　The evolutionary theory explains the differences in sleep among creatures．Why do eats, for instance, sleep so much, while horses sleep so little?Surely cats do not need five times as much repair and restoration as horses do．But cats can afford to have long periods of inactivity because they spend little time eating and are unlikely to be attacked while they sleep．Horses must spend almost all their waking hours eating, because what they eat is very low in energy value．Moreover, they cannot afford to sleep too long or too deeply, because their survival(生存)depends on their ability to run away from attackers．

(1)

The author uses the example of the robot in space exploration to tell us ________．
[　　]
A．	the differences between robots and men
B．	the reason why men need to sleep
C．	about the need for robots to save power
D．	about the danger of men working at night

(2)

Evolution has programmed man to sleep at night chiefly to help him ________．
[　　]
A．	keep up a regular pattern of life
B．	prevent trouble that comes looking for him
C．	avoid danger and inefficient labour
D．	restore his bodily functions

(3)

According to the author, we cannot sleep well when we ________．
[　　]
A．	are worrying about our safety
B．	are overworked
C．	are in a tent
D．	are away from home

(4)

Cats sleep much more than horses do partly because cats ________．
[　　]
A．	need more time for restoration
B．	are unlikely to be attackers
C．	axe more active than homes when they are awake
D．	spend less time eating to get enough energy

(5)

Which of the following is the main idea of the passage?
[　　]
A．	Evolution has equipped all creatures with a regular pattern of sleeping and waking．
B．	The study of sleep is an important part of the evolutionary theory．
C．	Sleeping patterns must be taken into consideration in the designing of robots．
D．	The sleeping pattern of a living creature is determined by the food it eats．

查看答案和解析>>

科目：高中英语 来源：101网校同步练习　高三英语　人民教育出版社(新课标A　2002-3年初审) 人教版 题型：050

阅读理解：

　　Several years ago, my parents, my wife, my son and I ate at one of those restaurants where the menu is written on a blackboard．After a wonderful dinner, the waiter set the check in the middle of the table．That’s when it happened：my father did not reach for the check．

　　Conversation continued．Finally I realized that I should pick up the check!After hundreds of restaurant meals with my parents, after a lifetime of thinking of my father as the one with dollars, it had all changed．I reached for the check, and my view of myself suddenly changed．I was an adult．I was no longer a kid．

　　Some people mark off(区分)their lives in years, I measure mine in small events．I didn’t become a young man at a particular age, like 16, but rather when a kid who wandered in the streets called me “mister．” These events in my life are called “milestones”(里程碑)

　　There have been other milestones．The cops(policemen)of my youth always seemed big, even huge, and of course they were older than I was．Then one day they were suddenly realized that all the football players in the game I was watching were younger than I was．They were just big kids．With that milestone gone was the dream that someday, maybe I, too, could be a football player．Without ever having reached the hill, I was over it．

　　I never thought that I would fall asleep in front of the TV set as my father did．Now it’s what I do best．I never thought that I would go to the beach and not swim, yet I spent all of August at the shore and never once went into the ocean．I never thought that I would appreciate opera, but now the combination of voice and orchestra attract me．I never thought that I would prefer to stay home in the evenings, but now I find myself passing up parties．I used to think that people who watched birds were strange, but this summer I fond myself watching them, and maybe I’ll get a book on the subject．I feel a strong desire for a religious belief that I never thought I’d want, feel close to my ancestors(祖先)long gone, and echo my father in arguments with my son．I still lose…

　　One day I bought a house．One day－what a day!–I became a father, and not too long after that I picked up the check for my own father．I thought then it was a milestone for me．One day, when I was a little older, I realized it was one for him, too, another milestone．

(1)

The tone established in the passage is one of ________．
[　　]
A．	sad regret
B．	amusement
C．	happiness
D．	deep feeling

(2)

The author mentions the event in the restaurant because ________．
[　　]
A．	that was one of his milestone
B．	he paid the bill but he didn’t want to
C．	he became a father with dollars
D．	that was the last restaurant meal with his parents

(3)

“Then they were suddenly neither．” Suggests that ________．
[　　]
A．	suddenly they became older than I was
B．	suddenly I knew that they was neither bigger nor older than I was
C．	suddenly I realized that I made mistake
D．	suddenly I found myself no longer a kid

(4)

Which of the following best expresses the author’s thinking?
[　　]
A．	One day is worth two tomorrow
B．	To save time is to length life
C．	When an opportunity is lost, it never comes back to you
D．	Time and tide wait for no man

查看答案和解析>>

同步练习册答案

练习册

高中

初中

小学