your body get rid of harmful toxins. Trampolining has benefits similar to those of running, but without too much stress on knees and ankles.

If you would like to start trampolining, you may first need to ask a doctor to make sure it's a safe activity for you. It's easy to find an inexpensive trampaline, but it should be well made and strong enough to support your weight. To avoid accidents, some trampolines have 8 safety net around them. Remember: whenever you are on a trampoline, be careful not to jump near the edge of it.

Here are a few exercises for beginners,

★High Knee Lift. Raise one knee at a time. Lift your knee higher than you usually do when you are running. ★Star Jump. Jump into the air and spread your arms and legs into a star shape. As you gain more confidence, practice more difficult levels:

★Tuck Jump. At the top of your jump, bring the knees to the chest. with the arms holding the legs. ★Pike Jump. Jump high, bring the legs up, and point the toes forward. Touch your toes with hands. There are many more exercises you can try. Happy trampolining! 29. According to the passage, what benefit can we get from trampolining? A. It helps with bone growth. B. It cures illnesses in our knees. C. It helps reduce stress on musecles.

D. It prevents ears from being hurt.

30. How can we do trampolining safely? A. Buy an expensive trampoline. B. Jump in the center of a trampoline. C. Choose a trampoline without a net D. Lose weight before starting trampolining.

31. Which picture shows Tuck Jump?

A. B.

C. D.

32. This passage introduces _______________. A. an exercise to improve our fitness

.B. an exercise to gain self-confidence

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C. a way to keep balance when we jump D. a way to avoid accidents when exercising

【答案】29. A 30. B 31. D 32. A 【解析】

文章大意：本文介绍了蹦床的优点，以及开始蹦床时需要注意的事项。并对初学者给出了一些合适的练习方法。 【29题详解】

细节理解题。根据文中的信息trampolining has many advantages. It helps bones and muscles grow，可知蹦床有很多优点，它可以帮助骨骼和肌肉生长，故答案选A。 【30题详解】

细节理解题。根据文中的信息Remember: whenever you are on a trampoline, be careful not to jump near the edge of it. 记住：当你在蹦床上的时候，小心不要跳到它的边缘。由此可推知，在做蹦床运动时，在蹦床的中心跳是安全的，故答案选B。 【31题详解】

理解判断题。根据文中的信息Tuck Jump. At the top of your jump, bring the knees to the chest. with the arms holding the legs. 塔克跳。在你跳跃的顶端，把膝盖伸向胸前。双臂抱着腿。结合图片，可知D选项符合题意，故答案选D。 【32题详解】

主旨大意题。通读全文可知，本文主要讲的是蹦床运动，并详细介绍了蹦床对我们身体的好处，还对初学者给出了一些合适的练习方法。结合选项可知A选项an exercise to improve our fitness“一项提高我们身体素质的运动”符合题意，故答案选A。

C

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Many objects in the universe are invisible,but they send radio waves. The radio telescope thus appeared, and it is considered one of the greatest inventions in the twentieth century. Reber built the world's first radio telescope in 1937. Ryle and Hewish developed radio telescope systems for the location of weak radio sources, and they shared the Nobel Prize for Physics in 1974.

A radio telescope is usually made up of:

One or more antennas to collect the radio waves. Most antennas are made in the shape of a dish to collect and reflect, the radio waves to the sub-reflector, in the same way as a curved mirror focuses visible light to one point.

A receiver and amplifier to receive the radio waves from the sub-reflector, and make these weak radio waves strong enough to be recorded and turned into electronic signals. To make an amplifier sensitive enough, it is usually cooled to, very low temperatures (e. g. as low as -270℃）.

A recorder to keep a record of the electronic signals. Most :radio telescopes today keep the signals to the computer's memory disk for astronomers to analyze later.

Radio wavelengths are much longer than those of visible light and the radio waves from deep space are always weak. To catch Radio wavelengths are much longer than those of visible light,and the radio waves from deep space are always weak. To catch these waves, radio telescopes usually have huge antennas. The sizes of most antennas in use today are around 50 to 300 metres in diameter. The antenna of FAST in Guizhou, China, the latest and largest radio telescope in the world, is 500 metres in diameter, as large as the size of 30 football fields.

To avoid interferences, and keep the telescopes sensitive, radio telescopes are built in places where there are no human radio waves or electronic signals. For example, FAST is 5 kilometres away from the closest village and 25

,

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kilometres away from the nearest town.

Radio telescopes create pictures of the sky, not in visible light, but in radio waves. This is extremely useful, because there are objects that can't be seen, objects that we wouldn't even know without radio telescopes. 33. Radio telescopes help collect ____________ from the universe A. light

B. objects

C. radio waves

D. visible signals

34. Most antennas of radio telescopes are made in the shape of a dish to ____________. A. make the antennas strong enough B. increase the number of radio waves C. turn radio waves into electronic signals D. focus radio waves on the sub-reflector

35. The underlined word \interferences\ A. the noises made by villagers and animals B. the sounds from the radios and televisions C. the people who go to Guizhou to watch FAST work D. the radio waves and electronic signals from humans 36. What have we done with the help of radio telescopes? A. We have received pictures of deep space. .B. We have discovered unknown lives in the universe. C. We have found some unknown objects in the universe. D. We have turned the radio waves from space into light. 【答案】33. C 34. D 35. D 36. C 【解析】

文章大意：本文主要介绍了无线电天文望远镜，详细介绍了它的发明、构成、工作原理、作用等。

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