Temperature is measured by means of a thermometer (温度计). One general form of thermometer depends upon the fact that most solids and liquids expand as their temperature rises. There are one or two exceptions. There is, for instance, a kind of steel called invar (from “invariable”) which does not change its dimensions as temperature changes; it is valuable for making pendulums (钟摆), since, if the length of a pendulum changes, its time of vibration changes. It is also used for making very accurate measuring scales. In both cases, then, changes of atmospheric temperature have no effect if invar is used.
Another exception is that very odd liquid, water, which has many strange properties (特性). As water gets colder it contracts (收缩), which is ordinary behavior, until it reaches the temperature of 30℃. above freezing point. After that, as it gets colder, it expands. This is fortunate---for considering the freezing of a pond. As the water on top gets colder, it shrinks; and so, volume for volume, it becomes heavier and sinks. This goes on until all the pond is at 30℃, but after that, as the water becomes colder it expands. Therefore the colder water stays on top and freezes, covering the pond with ice. If the water went on contracting down to the freezing point, the pond would become a solid block of ice in the end. This would not worry people who live in hot climates, but it would be very serious for those who live in cold climates, especially for those who want to break the ice and catch fish which live in the cold water beneath. Invar is valuable for making pendulums because _______.
A.it can hardly change its shape or size as temperature changes. |
B.it will change its dimensions without the change of temperature. |
C.its time of vibration doesn’t change if its length changes. |
D.its time of vibration does not change if its length changes. |
As water gets colder after reaching the temperature of 30℃. it will _______.
A.contract | B.shrink | C.expand | D.freeze |
Which of the following statements is true, according to this passage?
A.Only invar can be used to make a thermometer. |
B.Only water can be used to make a thermometer. |
C.Both invar and water can be used to make a thermometer. |
D.Neither invar nor water can be used to make a thermometer. |
The best title of this passage is most likely to be _____.
A.Temperature Measurement | B.Two Exceptions |
C.Uses of Invar | D.Properties of Water |
In many societies, there is often greater acceptance of light skin than dark skin. Light skin may be seen as a mark of beauty, intelligence and success. These beliefs can lead to social pressures even within the same racial or ethnic group, if some members are darker skinned than others.
The result is that skin lightening has become a common activity across Africa, Asia and other areas of the world. More and more people with dark skin are using skin-lightening products, even if it means they may face health risks.
They believe that having whiter skin will improve their lives. Many people think they will have a better chance of getting a job or marrying into a better family. Or they want to look like what their society generally considers beautiful.
Some beauty care products and soaps contain chemicals that make skin lighter. This is also called bleaching. But some of the chemicals are extremely dangerous. One of the most dangerous is hydroquinone(对苯二酚).
Hydroquinone has been banned in several countries. This chemical has been connected to kidney damage and some kinds of cancer. It also causes low birth weight in babies when mothers –to-be use it during pregnancy.
At first, bleaching products make the skin color lighter. But after long-term use they can cause problems. They could even make some skin darker.
The chemicals in the products block and break down the natural process that gives color to skin. The skin loses its natural barrier(障碍)to protect against sunlight. Then the skin can become thick and discolored. Usually the person will use more of the product in an effort to correct the problem, but this only makes it worse.
Fatimata Ly treats skin conditions in the Senegalese capital, Dakar. Doctor Ly says skin bleaching has become a problem throughout Senegal. She says the chemicals are now more dangerous because they are stronger. Some cases have resulted in blackened fingernails, infections and permanent(永久的)skin damage.
And these are not the only risks. Experts say some people who change their skin color suffer emotional damage. They feel regret and sadness. They feel that instead of risking their health, they should have learned to love and accept their skin color as it was.What is the text mainly about?
A.The advantages of light skin | B.Introducing skin lightening products |
C.The harmfulness of Hydroquinone | D.The health risks of bleaching |
What does the underlined word “bleaching” refer to?
A.The process of removing the color |
B.The process of making the skin whiter |
C.The chemicals that make things white |
D.The chemicals that protect skin against sunlight |
Why do people want to make their skin lighter?
A.Because they all want to look more beautiful. |
B.Because they all want to marry into better families. |
C.Because they want to find better jobs. |
D.Because they want to improve their lives. |
Skin bleaching may cause the problem of ______.
A.emotional problems | B.kidney cancer | C.lighter![]() |
D.low birth rate |
The author holds a/ an ______ attitude towards skin lightening.
A.positive | B.negative | C.supportive | D.optimistic |
DNA is one of the most important discoveries in science. DNA is the plan for the human being, as a blueprint is the plan for a building. DNA makes a person look the way he does. A person’s DNA comes from a mixing of his parents’ DNA. That’s why a child looks like his parents. But, besides controlling things such as height and hair color, DNA can also give people diseases. Scientists are now studying DNA to cure diseases.
In the seventies, scientists developed a process called recombinant or RDNA. Although it sounds difficult to understand, RDNA simply means taking DNA from one animal or plant and putting it into another. By doing so, scientists can create new beings. In doing so, scientists can better understand DNA, especially what parts of DNA do what. After they understand DNA, scientists can begin to cure diseases. Often, the new being created will itself be the cure.Besides curing diseases, RDNA research can also do other things. For example, scientists in Japan have already created “super-trees”. Trees help humans, because they take CO2, which poisons humans, from the air and turns it into oxygen, which lets humans breathe. “Super-trees” do this too, but do it much faster. As things such as cars and factories have already put much CO2 in the area, “super-trees” are badly needed.
Unfortunately, there is a serious danger in RDNA research. Scientists want to create animals to cure old diseases, but these new animals may also create new diseases. It will be a serious problem if the animals escape from the science laboratory and into nature. As these animals are not natural, they may let loose many new powerful diseases.
As a result, RDNA research will create many solutions, but it will also create many problems. From the passage, we can know that a boy looks like his parents because______.
A.he is son of his parents. |
B.his parents’ DNA decides his appearance. |
C.he has received DNA from his father or his mother. |
D.scientists have put some of his parents’ DNA into him. |
What does the underlined expression “let loose” probably mean?
A.let … go free | B.get rid of |
C.absorb | D.survive |
What is the best title for the passage?
A.The DNA Research in Japan |
B.A New Way of DNA Research in Japan. |
C.The Causes and Effects of DNA Research |
D.The Advantages And Disadvantages of RDNA |
The following statements are true about RDNA research EXCEPT ______.
A.the research has been stopped because the created animals carry viruses |
B.“super-trees” might be widely planted around the world |
C.scientists have not completely understood DNA |
D.RDNA research will benefit human beings a lot |
You might find this passage in / on a ________.
A.fashion magazine | B.novel | C.scientific newspaper | D.sports newspaper |
Life gets noisier every day and very few people can be free from noise of some sort or another. It doesn’t matter where you live-in the middle of a modern city, or a faraway village-the chances that you will be disturbed by jet aeroplanes, transistor radios, oil-powered engines, etc. are almost everywhere .We seem to be getting used to noise, too. Some people feel quite lonely without background music while they are working.
Scientific tests have shown that total silence can be very frightening experience for human beings. However, some people enjoy listening to pop music which is very loud, and this can do harm to their eardrums(耳鼓).The noise level in some disco is far above the usual safety level for heavy industrial areas.
A recent report about noise and concentration(专心) suggested that although a lot of people say that any noise disturbs their concentration, what really affects their ability to concentrate is a change in the level of noise. It goes on to say that a background noise, which doesn’t change too much (music, for example) may even help people to concentrate.The best title for this passage is _______________.
A.Noisy Life | B.Background Noise |
C.Disturbed Concentration | D.Changeable Noise |
From this passage, the pollution of noise _______________.
A.doesn’t matter much | B.has become worse everywhere |
C.has become better in big cities | D.has become better in villages |
“Background music” in the passage means _______________.
A.music played in the concert | B.a kind of noise coming into your ears |
C.music helps people to concentrate | D.music played while people are working |
Some people may have their hearing hurt _______________.
A.while they are in completely silence | B.while they are dancing violently |
C.while they are listening to loud pop music | D.while they are listening to soft music |
Scientists have discovered that what prevents people from concentrating is _____.
A.any kind of noise | B.great changes in level of noise |
C.background noise | D.various background music |
Goals can help you do, be and experience everything you want in life. Instead of just letting life happen to you, goals allow you to make your life happen.
Successful and happy people have an idea of how their life should be and they set lots of goals to help them succeed. By setting goals you are taking control of your life. It’s like having a map to show you where you want to go. Think of it this way. There are two drivers. One has a destination in mind which is laid out for her on a map. She can drive straight there without any wasted time or wrong turns. The other driver has no goal or destination or map. She starts off at the same time from the same place as the first driver, but she drives without an aim around, never getting anywhere, just using up gas and oil. Which driver do you want to be?
Winners in life set goals and follow through on them. Winners decide what they want in life and then get there by making plans and setting goals. Unsuccessful people just let life happen by accident. Goals aren’t difficult to set―and they aren’t difficult to reach. It’s up to you to find out what your goals and ideals(理想)really are.
Research tells us that when we write a goal down, we are more likely to achieve. Written goals can be reviewed regularly,and have more power. Like a contract with yourself, they are harder to neglect(忽视)or forget. Also when you write your goals in a particular way, you are able to make yourself be continuously alert(警觉)to situations that will further your goals.The writer gave the example of two drivers to show.
A.how stupid the first driver was | B.the importance of having a map and right direction |
C.how stupid the second driver was | D.the importance of setting goals |
According to the passage, successful people are different from unsuccessful ones because.
A.the successful people set goals for everything and can get help from others |
B.the unsuccessful people always set unrealistic plans for themselves |
C.the successful people set goals in their lives and make plans to carry it out |
D.the unsuccessful people make plans for everything but can not work hard |
According to the passage, the most important thing in realizing one’s ideal is to.
A.try to be realistic about one’s ability |
B.let others help him or her to make his or her dream come true |
C.let others understand him or her first,then work together with them |
D.have a clear mind of what he or she wants in life |
Which of the following is TRUE according to the passage?
A.Goals can make you gain everything you want in life |
B.Only successful people can be happy |
C.If you want to succeed,you need a set long-term goals instead of short-term Goals |
D.When we put our goal down on papers, we are more likely to succeed |
Which is the best title for the passage?
A.Goals help you succeed | B.How to succeed |
C.Why we always failed | D.A research on setting goals |
Forty-two of the fifty American states offered some kind of public online learning this past school year.One state,Michigan,now requires all students to have an online learning experience before they finish high school.Even the idea of a school has changed since the rise ofthe Internet in the 1990s.
A new report from the Center for Evaluation and Education Policy at Indiana University says eighteen states have full-time virtual schools.There are no buildings.All classes are online.
Florida started the first statewide public virtual school in the United States in 1997.Today,the Florida Virtual School offers more man ninety courses.56,000 students were enrolled as of December.Almost sixty percent were female.The school's website says each student was enrolled in an average of two classes.
Florida Virtual School has now opened the Florida Virtual Global School.Students in other countries pay for classes.Janet Heiking teaches an English class.She lives in Indianapolis, Indiana.Her students live as far away as Africa and Japan.She says they are taking her Advanced Placement class to prepare for attending an American college.They can earn college credits by passing the AP test.
So how good are virtual schools? Studies have shown mixed results, as a new report from Indiana University notes.For example, students at Florida Virtual School earned higher grades than those taking the same courses the traditional way.And they scored higher on a statewide
test.But virtual school students in Kansas and Colorado had lower test scores or performed at a lower level than traditional learners.Studies also find that virtual schools may not save much in operating costs.
Education experts say the mixed results suggest the need for more research to find the best ways to teach in virtual schools.A1so, they say schools of education need to train more teachers to work in both real and virtual classrooms.A virtual school is one that___________.
A.is set up after the rise of the Internet |
B.uses textbooks as a main teaching resource |
C.uses computer-based resources and has no teachers |
D.has online classes and no real classrooms |
The first statewide public virtual school in the USA was started in ________ .
A.Florida | B.Indiana | C.Michigan | D.Colorado |
Florida Virtual School is open to ________.
A.students in Indiana |
B.students only around the USA |
C.students across the world |
D.only foreign students |
Foreign students take Advanced Placement classes for the eventual purpose of __________ .
A.earning college credits |
B.entering an American college |
C.learning advanced science |
D.passin![]() |
From the passage we learn that________.
A.the majority of virtual school students in Florida are male |
B.all senior students m Michigan have an online learning experience |
C.virtual schools are better than traditional schools |
D.both real and virtual classrooms need more trained teachers |