Why do people shrink?
Did you ever see the movie Honey,I shrunk the kids? It’s about a wacky dad(who’s also a scientist)wh0 accidentally shrinks his kids with his homemade miniaturizing invention.0ops! ____(1).
For older people,shrinking isn’t that dramatic or sudden at all. It takes place over years and may add up to only one inch or so off of their adult height(maybe a 1ittle more,maybe less), and this kind of shrinking can’t be magically reversed,although there are things that can be done to stop it or slow it down._____(2).
There are a flew reasons.As people get older,they generally lose some muscle and flat from their bodies as part of the natural aging process.Gravity (the force that keeps your feet on the ground) take hold,and the bones in the spine,called vertebrae,may break down or degenerate,and start to collapse into one another_____ (3).But perhaps the most common reason why some older people shrink is because
of osteoporosis.
0steoporosis occurs when too much spongy bone tissue(which is found inside of most bones)is broken down and not enough new bone material is made.______(4). Bones become smaller and weaker and can easily break if someone with osteoporosis is injured. Older people—especially women,who generally have smaller and lighter bones to begin with--are more likely to develop osteoporosis.As years go by,a person with osteoporosis shrinks a little bit.
Did you know that every day you do a shrinking act? You aren’t as tall at the end of the day as you are at the beginning.That’s because as the day goes on,water in the disks of the spine gets compressed(squeezed)due to gravity,making you just a tiny bit shorter.Don’t worry,though._____(5)
A.They end up pressing closer together,which makes a person lose a little height and become shorter.
B.0rice you get a good night’s rest,your body recovers,and the next morning,you’re standing tall again. C.0ver time.bone is said to be lost because it’s not being replaced.
D.Luckily,there are things that people cab do to prevent shrinking.
E.The kids spend the rest of the movie as tiny people who are barely Visible while trying to get back to their normal size.
F.But why does shrinking happen at all ?
第 21 题 请选择(1)处的最佳答案.
Droplets and ice crystals behave somewhat like dust in the air made visible in a shaft(束) of sunlight. To the casual observer, dust seems to act in a totally random fashion, moving about wildly without fixed direction. But in fact dust particles are much larger than water droplets and they finally fall. The cloud droplet of average size is only 1/2,500 inch in diameter. (78)It is so small that it would take sixteen hours to fall half a mile in perfectly still air, and it does not fall out of moving air at all. Only when the droplet grows to a diameter of 1/125 inch or larger can it fall form. the cloud. The average raindrop contains a million times as much water as a tiny cloud droplet. The growth of a cloud droplet to a size large enough to fall out is the cause of rain.
What is the main topic of the passage?
A.The mechanics of rain.
B.The climate of North America.
C.How gravity affects air current.
D.Types of clouds.
Cream and butter contain pretty much the same substances, so why cream should sour much faster has been a mystery. Both are emulsions—tiny globules(小球) of one liquid evenly distributed throughout another. "The difference lies in what's in the globules and what's in the surrounding liquid", says Brocklehurst, who led the investigation. In cream, fatty globules drift about in a sea of water. In butter, globules of a watery solution are locked away in a sea of fat. The bacteria which make the food go bad prefer to live in the watery regions of the mixture. "This means that in cream, the bacteria are free to grow throughout the mixture", he says.
When the situation is reversed, the bacteria are locked away in compartments(密封仓) buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients. They also slowly poison themselves with their waste products. "In butter, you get a self-limiting system which stops the bacteria growing", says Brocklehurst. The researchers are already working with food companies keen to see if their products can be made resistant to bacterial attack through alterations to the food's structure. Brocklehurst believes it will be possible to make the emulsions used in salad cream, for instance, more like that in butter. The key will be to do this while keeping the salad cream liquid and not turning it into a solid lump.
The significance of Brocklehurst's research is that ______.
A.it suggested a way to keep some foods fresh without preservatives
B.it discovered tiny globules in both cream and butter
C.it revealed the secret of how bacteria multiply in cream and butter
D.it found that cream and butter share the same chemical composition
Part A
Directions:
You will have an English class next Friday, but you can’t attend it. Write a letter to your English teacher, Mr. Wang, to ask for leave. Tell him:
1) why you ask for leave,
2) what you will do to make up for it.
You should write about 100 words neatly on ANSWER SHEET 2. Do not sign your own name. Use “Li Ming” instead. (10 points)
The marvel of the machine age, the electronic computer has been in use only since 1946. It can do simple computations—add, subtract, multiply, and divide—with lightning speed and perfect accuracy. It can multiply two 10-digit numbers in 1/1, 000 second, a problem that would take an average person five minutes to do with pencil and paper. Some computers can work 500, 000 times faster than any person can.
Once it is given a program, that is, a carefully worked-out set of instructions devised by a technician trained in computer language, a computer can gather a wide range of information for many purposes. For the scientist it can get information from outer space or from the depths of the ocean. In business and industry the computer prepares factory inventories, keeps track of sales trends and production needs, mails dividend checks, and makes out company payrolls. It can keep bank accounts up to date and make out electric bills. If you are planning a trip by plane, the computer will find out what route to take and what space is available.
Why does the author regard the electronic computer as the marvel of the machine age?
A.Because electronic computers are rare.
B.Because people know little about electronic computers.
C.Because electronic computers can do much more kinds of work that human beings can't.
D.Because electronic computers have been widely suspected.
Life on Mars
Perhaps more than anything else, scientists are eager to find out if Martian life existed in the past—or still exists.【61】telescopes first zoomed in【62】Mars in the 17th century, people have conjured up a wild【63】of images or what Martians might look like. But space probes like the 1997 Sojourner land rover have yielded no evidence of such alien beings.
Most experts agree that if life did at one time evolve on Mars, finding evidence of that life—which would likely take the form. of tiny organisms—won't be easy.【64】, many scientists are optimistic. "We've got organisms on Earth that adapted to life deep【65】the surface in underground water wells, " says Stephen Clifford. "【66】life like that evolved on Mars four billion years ago, there's no reason why it【67】today. "
【68】last year's disappointing losses, the future of Martian exploration looks【69】This year, two major
films about fictitious Mars missions—Red Planet and Missions to Mars—are certain to heighten interest in our planetary neighbour. More important, plans for new sets of NASA orbiters and landers—one to launch in 2001 , the other in 2003—are already in the works. Without a doubt, each new mission will inch scientists closer to【70】the mysteries of planet Mars.
(61)
A.When
B.Before
C.Ever since
D.Ever
已知描述某LI系统的微分方程,y"(t)+3y'(t)+2y(t)=3f(t),且y(0_)=1,y′(0_)=-1,f(t)=ε(t)。
求:(1)系统函数H(s)
(2)系统的零状态响应yzs(t)
(3)系统的零输入响应yzi(t)
“Are you crazy?” people around him shouted as Alex Bien, a 33-year-old immigrant(移民), ran toward three cars in a chain accident along the highway in Miami, which were burning down. Alex didn’t think twice.
The article “Against the Flames” reported how he put out the fire on a car and pulled a couple out of another. But when here turned to his own car, steam was coming out from it. It was damaged beyond repair.
Back in his tiny flat, alone and with little money, Alex didn’t know what to do. He was already working, going to college and supporting his wife, Aline, and children back in Haiti. He worried about his wife’s health; doctors thought she had cancer(癌症). Every cent was important to him. And now this.
With in weeks of reading the article, readers sent hundreds of letters offering jobs, money and best wishes. One delivered a car-used, but in fine condition. Others helped Aline come to Miami, where a medical team found out it was not cancer.
Readers also wrote to U.S. government officials to support the immigration of Alex’s family to Miami. Consul General Roger Daley even invited Alex to discuss the matter. Aline, to get her with their children, joined Alexin Miami this past March. Alex says, “I would like to say a beautiful thanks to the readers. There are good people every where in this world.”
Why did people say that Alex was crazy?????
A.He had an accident
B.He made a fire on the highway
C.He burned his car
D.He ran toward the burning cars
What do we know about Alex from the text?A.He and his wife worked in the U.S.
B.He was a full-time student in Haiti
C.He was an immigrant with little money
D.He wrote the article “Against the Flames”
What did Roger Daley invite Alex to discuss?A.Alex’s new job as a news reporter
B.The medical treatment of Alex’s wife
C.Alex’s further studies at a U.S.university
D.The immigration of Alex’s family to the U.S.
What made Alex say “There are good people everywhere in this world”?A.Some strangers repaired his car free of charge
B.Some people supported his children’s education
C.Many readers of the article tried to help him out
D.His friends sent doctors to treat his wife in Haiti
t_3wz. mp3
In a new school, Liu Hui wonders how to build a good relationship with his new classmatesand is asking for Li Hua's advice.
Li Hua: Hi, Liu Hui. Have you got something(1).____?
Liu Hui: Hmmm, I'm . . . a little . . . upset.
Li Hua: Anything wrong? It's only (2).____ the first semester. How are you getting on with your school life?
Liu Hui: My classmates are from different places, with all those different backgrounds. I'm not sure how to (3).____them.
Li Hua: That's not difficult.(4).____to find common topics to talk with them about.
Liu Hui: What kind of common topics?
Li Hua: Hobbies, games, hometown, family and so on.
Liu Hui: Well. I see. Breaking the ice is a good way to(5).____. Thank you very much.
Li Hua: My pleasure.
(1).____
A.get along with
B.the beginning of
C.on your mind
D. Try your best
E. make friends
(2).____
A.get along with
B.the beginning of
C.on your mind
D. Try your best
E. make friends
(3).____
A.get along with
B.the beginning of
C.on your mind
D. Try your best
E. make friends
(4).____
A.get along with
B.the beginning of
C.on your mind
D. Try your best
E. make friends
(5).____
A.get along with
B.the beginning of
C.on your mind
D. Try your best
E. make friends
A.Good
B.Quite well
C.No problem
D.Not bad
In order to support this argument, the writer gives the example that ______ .
A.a machine using solar energy efficiently has already been developed
B.the sun is our final source of power
C.man uses only a tiny part of the sun's energy
D.the part of the sun's energy we use is used indirectly