英语周报：2009年6月英语四级听力全真模拟题(二)

　　Section B

　　Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A)， B)， C) and D). Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre。

　　Passage One

　　What makes it rain? Rain falls from clouds for the same reason anything falls to Earth. The Earth’s gravity pulls it. But every cloud is made of water droplets or ice crystals. Why doesn’t rain or snow fall constantly from all clouds? The droplets of ice crystals in clouds are very small. The effect of gravity on them is minute. Air currents move and lift droplets so that net downward displacement is zero, even though the droplets are in constant motion。

　　Droplets and ice crystals behave somewhat like dust in the air made visible in a shaft of sunlight. To the casual observer, dust seems to act in a totally random fashion 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 1/2500 inch in diameter. It is so small that it would take sixteen hours to fall 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 from the clouds. 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 and other forms of precipitation. This important growth process is called “coalescence。”

　　Questions 26 to 28 are based on the passage you have just heard。

　　26. What is the main topic of the passage?

　　27. Why don’t all ice crystals in clouds immediately fall to Earth?

　　28. In this passage, what does the term “coalescence” refer to?

　　Passage Two

　　Good locks on all outside doors and first floor windows are essential to a home’s security and will go a long way towards discouraging burglars. But an added protective device that is increasingly being used in homes is the burglar alarm system, which sounds a loud bell when someone tries to break in. Although this will not always prevent entry by a professional burglar, it is often enough to scare off thieves who account for a high percentage of residential break-ins。

　　Security alarm systems have all been available for many years and have long been common in commercial and industrial establishments and in large homes. But until the last few years, these system were almost always professionally installed because they required complicated wiring techniques, individualized design and sometimes lots of carpentry---all of which made them expensive。

　　To answer the demand for low-cost alarm systems that can be easily installed, several companies now make alarms that are specifically designed as “do-it-yourself。” These systems come with detailed installation instructions and usually do not require inside-the-wall-wiring。

　　Questions 29 to 31 are based on the passage you have just heard。

　　29. Which statement is true according to the passage?

　　30. According to the passage, why have security alarm system been expensive for many years?

　　31. What’s the main idea of this passage?

　　Passage Three

　　Around the world more and more people are taking part in dangerous sports and activities. Of course, there have been people who have looked for adventure---those who have climbed the highest mountains, explored unknown parts of the world or sailed in small boats across the greatest oceans. Now, however, there are people who seek an immediate thrill from a risky activity which may only last a few minutes or even seconds。

　　I would consider bungee jumping to be a good example of such an activity. You jump from a high place 200 meters above the ground with an elastic rope tied to your ankles. You fall at up to 150 kilometers an hour until the rope stops you from hitting the ground. It is estimated that 2 million people around the world have now tried bungee jumping. Why do people take part in such activities as these? Some psychologists suggest that it is because life in modern societies has become safe and boring. Not very long ago, people’s lives were constantly under threat. They had to go out and hunt for food, diseases could not easily be cured, and life was a continuous battle for survival。

　　Nowadays, according to many people, life offers little excitement. They live and work in a comparatively safe environment; they buy food in shops; and there are doctors and hospitals to look after them if they become ill. The answer for some of these people is to seek danger in activities such as bungee jumping。

　　Questions 32 to 35 are based on the passage you have just heard。

　　32. What does the bungee jumping mean?

　　33. Why do people take part in dangerous sports nowadays?

　　34. What’s the author’s attitude towards dangerous sports?

　　35. Which title is suitable for this passage?