大学英语四级阅读理解练习 九

　　Directions: There are 4 passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C) and D). You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the centre.
　　Questions 1 to 5 are based on the following passage:
　　Rockets come into all sizes. Any rocket is interesting and often exciting, but there is one that also promises to be wonderful fun for the pilot. This rocket is designed to carry one person through the air for short distances.
　　Imagine a person able to rise higher than the treetops, to soar like a wingless bird over hills, streams, or even buildings. Then, just by turning a handle, he or she can settle gently to earth again. All this is possible with a fascinating invention, hardly larger than a life jacket, called a rocket belt.
　　The rocket belt looks like a padded vest（护垫背心）with two steel tanks on the back and a handgrip（柄）extending over each shoulder. Turning the left handgrip lets the pilot rise into the air, higher than the tops of trees. Turning the right handgrip lets him or her speed ahead, like a wingless bird. By controlling the right grip and body motions, the pilot can come to a stop in the air. Then, by regulating the thrust with the left hand, the pilot can come back to earth gently.
　　A rocket engine may be thought of as a special kind of furnace in which fuels are burned very rapidly at very high temperatures. The burning fuel creates hot gases. The hot gases then expand and push against the inside of the engine.
　　Imagine a steel cylinder（汽缸，泵筒体）with no openings except two tiny ones where fuel and oxygen enter.The fuel burns and gas is formed. This gas expands, pushing equally in all directions. Pressure becomes so great that, unless it is relieved, the cylinder will burst.
　　But before the steel cylinder can burst, the end opposite the fuel intake is suddenly opened and the hot gases rush out. More gases are formed instantly as the fuel continues to burn. The gases push against all parts of the cylinder except for the open end. This causes the cylinder to move away from the open end where there is no pressure.
　　1. This passage focuses on ________.
　　 A) rockets of all sizes
　　 B) the rocket belt
　　 C) rocket principles
　　 D) different rocket engines
　　2.The author has written the passage mainly for ________.
　　 A) young children
　　 B) experienced pilots
　　 C) scientists in the rocket field
　　 D) the common readers
　　3. What's the use of left handgrip in the rocket belt?
　　 A) It is used to control height, whether rising or landing.
　　 B) It is used to operate the engine.
　　 C) It is used to come to a stop in the air.
　　 D) It is used to fly a distance.
　　4.The author begins to discuss a rocket engine and a steel cylinder from the fourth paragraph on in order to _______.
　　 A) show that he is a specialist in this field
　　 B) prove that a rocket engine may be considered as a special kind of furnace
　　 C) make the readers understand how the rocket belt works
　　 D) tell the readers the functions of the engine and cylinder
　　5.In the following paragraph, which subject is the author probably going to talk in detail about ?
　　 A) how to train pilots
　　 B) how much a rocket belt cost
　　 C) where to buy a rocket belt
　　 D) functions of a rocket belt