Bacteria(细菌) are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in micron. One micron is a thousandth of a millimeter; a pinhead is about a millimeter across, Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron across. Thus, if you magnified a rounded bacterium a thousand times, it would be just the size of a pinhead, while a grown-up human enlarged by the same amount would be over a mile tall.
Even with an ordinary microscope(显微镜), you must look closely to see bacteria. Using a magnification of 100 times, one can hardly find bacteria. Nor can one make out anything of their structure(结构), of course. Only by using special colors, can one see that some bacteria have wavy-looking “hairs” called flagella. Others have only one flagellum. The flagella move round a central point, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can move along over surface by some little-understood “machinery”.
From the bacterial point of view, the world is a very different place from what it is to humans. To a bacterium, water is as thick as molasses(糖浆) is to us. Bacteria are so small that they are affected by the movements of the chemical molecules(分子) around them. Bacteria under microscopes, even those with no flagella, often jump up and down in the water. This is because they knock with the water molecules and are pushed this way and that.
36. The underlined word magnified means _______________.
A. enlarged                                                      B. widened                  
C. killed                                                          D. caught
37. We know from the passage that _______________ is the smallest.
A. a pinhead                                            B. a rounded bacterium 
C. a microscope                                        D. a rod-shaped bacterium
38. The relationship between a bacterium and its flagella is most nearly like which of the following?
A. A rider jumping on a horse back 
B. A ball being hit by a bet
C. A boat powered by a motor    
D. A door closed by wind
39. Why does the writer compares water to molasses in the third paragraph?
A. To tell us how difficult it is for bacteria to move through water.
B. To suggest that bacteria are fond of different liquids.
C. To show different chemicals are of different structures.
D. To show that bacteria are the best swimmers.
40. Which of the following is the main topic of the passage?
A. The characteristic (特点) of bacteria.      
B. How bacteria reproduce.
C. The various parts of a bacterium’s body    
D. How bacteria cause diseases.            

Bacteria(细菌) are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in micron. One micron is a thousandth of a millimeter; a pinhead is about a millimeter across, Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron across. Thus, if you magnified a rounded bacterium a thousand times, it would be just the size of a pinhead, while a grown-up human enlarged by the same amount would be over a mile tall.

Even with an ordinary microscope(显微镜), you must look closely to see bacteria. Using a magnification of 100 times, one can hardly find bacteria. Nor can one make out anything of their structure(结构), of course. Only by using special colors, can one see that some bacteria have wavy-looking “hairs” called flagella. Others have only one flagellum. The flagella move round a central point, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can move along over surface by some little-understood “machinery”.

From the bacterial point of view, the world is a very different place from what it is to humans. To a bacterium, water is as thick as molasses(糖浆) is to us. Bacteria are so small that they are affected by the movements of the chemical molecules(分子) around them. Bacteria under microscopes, even those with no flagella, often jump up and down in the water. This is because they knock with the water molecules and are pushed this way and that.

36. The underlined word magnified means _______________.

A. enlarged                                                      B. widened                  

C. killed                                                          D. caught

37. We know from the passage that _______________ is the smallest.

A. a pinhead                                            B. a rounded bacterium 

C. a microscope                                        D. a rod-shaped bacterium

38. The relationship between a bacterium and its flagella is most nearly like which of the following?

A. A rider jumping on a horse back 

B. A ball being hit by a bet

C. A boat powered by a motor    

D. A door closed by wind

39. Why does the writer compares water to molasses in the third paragraph?

A. To tell us how difficult it is for bacteria to move through water.

B. To suggest that bacteria are fond of different liquids.

C. To show different chemicals are of different structures.

D. To show that bacteria are the best swimmers.

40. Which of the following is the main topic of the passage?

A. The characteristic (特点) of bacteria.      

B. How bacteria reproduce.

C. The various parts of a bacterium’s body    

D. How bacteria cause diseases.            

Our sun is a star, and nine worlds move round it. Worlds like these are planets (行星).
But there are other stars, other suns. Not only thousands of them, but millions of them. Do different stars have planets? We can see the planets round our own sun. But we haven’t seen any more. The stars are too far away from us. Stars give out (发出)light, but the planets don’t have any light of their own. So we can’t see them. They’re too far, and too dark.
Still, we can tell that some stars have planets. While a big planet goes round, it pulls its star to one side. And sometimes we can see this, Then we know that the star has a planet.
For example, Barnard’s Star（巴纳德星）is a small red star. And it is the quickest star in the universe. But sometimes it moves slower, and then quicker again. We have know Barnard’s Star for many years, and now we are sure it has a planet.
【小题1】A star is a large body in the universe.it________.

A dam is a man-made structure built across a river. Most dams are built to control a river’s water flow, improve navigation and control flooding. However, some dams are built to produce hydro-electric power.

Hydro-electric power is produced as water passes through a dam, and into a river below. The more water that passes through a dam, the more energy is produced. Once a dam is built, a man-made lake is created behind the dam.

Electricity is produced by a kind of equipment called a turbine(水轮机). Turbines contain metal coils(线圈) surrounded by magnets(磁铁). When the magnets move round rapidly over the metal coils, electricity is produced. Turbines are located inside dams. The falling water makes the magnets go around the coils.

Dams provide clean energy, but they can also harm the environment. Species that use rivers to reproduce are often hurt by dams. In the Northwest of the US, the population of fishes has dropped from 16 million to 2.5 million since hydro-electric plants were built on the Columbia River. Dams all over the world have hurt some species. 

  The highest dam in the Unites States is located near Oroville, California. The Oroville Dam towers 230 meters and is more than a mile wide. This dam was built in 1968, 22 years after the Hoover Dam. The Hoover Dam, on the Nevada-Arizona border controls the Colorado river. It is 221 meters high and has 2.6 million hectare-meters of water.

The highest dam in the world is the Nurek Dam on the Vakhsh River in Tadzikistan, a country in central Asia. This dam is 300 meters tall. 

Which of the following statements is NOT true according to the passage?              

A. Some dams are built for controlling a river’s water flow.

B. Hydro-electric power is usually produced through a dam.

C. Dams can offer energy and they are harmless to the environment.

D. Generally speaking, where there is a dam, there is a man-made lake.

The third paragraph mainly tells us _____.       56-60 ADB                    

  A. how hydro-electric power is produced

  B. What a turbine is and how it works 

  C. how the magnets and the metal coils work

  D. how the falling water passes through a turbine                     

The dam which controls the Colorado river is ____.                  

A. the Oroville Dam  B. the Hoover Dam  C. the Nurek Dam  D. the Vakhsh Dam

Our sun is a star, and nine worlds move round it. Worlds like these are planets (行星).

But there are other stars, other suns. Not only thousands of them, but millions of them. Do different stars have planets? We can see the planets round our own sun. But we haven’t seen any more. The stars are too far away from us. Stars give out (发出)light, but the planets don’t have any light of their own. So we can’t see them. They’re too far, and too dark.

Still, we can tell that some stars have planets. While a big planet goes round, it pulls its star to one side. And sometimes we can see this, Then we know that the star has a planet.

For example, Barnard’s Star（巴纳德星）is a small red star. And it is the quickest star in the universe. But sometimes it moves slower, and then quicker again. We have know Barnard’s Star for many years, and now we are sure it has a planet.

A star is a large body in the universe.it________.

        A.moves round our sun            B.has light of its own      

        C.can also be called a world        D.both B and C

Which of the following is not true?

        A.The earth is one of sun’s worlds     B.There are millions of suns in the universe.       

 C. The worlds are very bright.        D.Some stars have planets

Barnard’s Star moves more quickly than _______.

        A.most stars          B.any other star       

 C.its planet           D.the planets round the sun

How can people know that there is a plante round Barnard’s Star?

        A.Sometimes they see that the planet pulls the star to one side and makes it move slower

.    B.The planet is shining.         

        C.The planet is next to our earth.        

D.The planet is a red one.