[外语类试卷]大学英语四级改革适用(阅读)模拟试卷231及答案与解析.doc
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1、大学英语四级改革适用(阅读)模拟试卷 231及答案与解析 Section C 0 If the salinity (含盐量 ) of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the su
2、btraction of water from the ocean by means of evaporation conversion of liquid water to water vapor. In this manner, the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind. The opposite of evaporation is preci
3、pitation (降水 ), such as rain, by which water is added to the ocean. Here the ocean is being diluted(稀释 ) so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by e
4、vaporation, or decreased by the addition of fresh water by precipitation or runoff (形成地表水部分的降雨 ). Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal reg
5、ions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas. A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly bene
6、ath freshly-formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water. In the Weddell Sea, off Antarctica, the densest water in the oceans is. formed as a result of this freezing process, w
7、hich increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world. 1 The best title of the passage can be “_“. ( A) Typical Oceans and Their Respective Features ( B) The Causes of the Changes in Salinity of Ocean Water ( C) Different Oce
8、ans Have Different Salinity ( D) The Precipitation and Evaporation of Oceans 2 Which of the following processes will increase salinity of ocean waters? ( A) Evaporation. ( B) Precipitation. ( C) Melting. ( D) Dilution. 3 According to this passage, the sea _ is likely to have the lowest salinity. ( A
9、) in tropical areas ( B) off Antarctica ( C) of high rainfall ( D) with abundant sunshine 4 The Weddell Sea_. ( A) is a good example of increased salinity in freezing sea water ( B) is much larger in area than the Arctic oceans ( C) has a much lower salinity now than ever ( D) has the denser water i
10、n its upper parts 5 Coastal regions are mentioned as cases where _. ( A) sea water is less salty because fresh water joins in ( B) rivers carry industrial exhaust into sea ( C) sea ice tends to melt more quickly than in the center of oceans ( D) heavy water sinks to the deeper portions of the oceans
11、 5 Although many of us may feel air-conditioners bring relief from hot, humid or polluted outside air, they pose many potential health hazards. Much research has looked at how the movement of air inside a closed environment such as an office buildingcan spread disease or expose people in the buildin
12、g to harmful chemicals. One of the more widely publicized dangers is that of Legionnaires disease, which was first recognized in the 1970s. This was found to have affected people in buildings with air-conditioning systems in which warm air pumped out of the systems cooling towers was somehow sucked
13、back into the air intake (通风口 ), in most cases due to poor design. The warm air, filled with bacteria, was combined with cooled, conditioned air and was then circulated around various parts of the building. Studies showed that even people outside such buildings were at risk if they walked past air e
14、xhaust pipes. Large air-conditioning systems add water to the air they circulate by means of humidifiers (湿度调节器 ). In older systems, the water used for this process is kept in special reservoirs, the bottoms of which provide breeding grounds for bacteria which can find their way into the ventilation
15、 (通风 ) system. The risk to human health from this situation has been highlighted by the fact that the immune systems (免疫系统 ) of approximately half of workers in air-conditioned office buildings have developed the ability to fight off the organisms found at the bottom of system reservoirs. But chemic
16、als called “biocides“ are added to reservoirs to make them germ-free, and they are dangerous in their own right in sufficient quantities, as they often contain compounds strongly linked to cancers. Finally, it should be pointed out that the artificial climatic environment created by air-conditioners
17、 can also affect us. In a natural environment, whether indoor or outdoor, there are small variations in temperature and humidity. Indeed, the human body has long been accustomed to these normal changes. In an air-conditioned living or work environment, however, body temperatures remain well under 37
18、 , our normal temperature. This leads to a weakened immune system and thus greater exposure to diseases such as colds and flu. 6 What do we know about Legionnaires disease from the passage? ( A) It was the most widely concerned office hazard. ( B) It can affect people both inside and outside the bui
19、lding. ( C) It happens only in air-conditioned office buildings. ( D) It does not develop in well-designed buildings. 7 In the old air-conditioned systems, bacteria first develop _. ( A) in the reservoirs ( B) in the ventilation system ( C) in the humidifiers ( D) in the air intake 8 The fact that a
20、bout half of workers developed the ability to fight off the bacteria may_. ( A) relieve peoples worry about the danger caused by the bacteria ( B) help people find an effective way to get rid of the bacteria ( C) reflect the serious danger brought by the bacteria ( D) cause serious disease such as c
21、ancers to people 9 The author most probably wants the readers to treat biocides with an attitude of_. ( A) caution ( B) trust ( C) enthusiasm ( D) criticism 10 The last paragraph implies that our immune system can be weakened when_. ( A) we live in an artificial climatic environment ( B) there are v
22、ariations in temperature and humidity ( C) our body temperatures often remain not high enough ( D) we are often exposed to diseases such as colds and flu 10 For centuries, in the countries of south and Southeast Asia the elephant has been an intimate part of the culture, economy and religion. And no
23、where more so than in Thailand. Unlike its African cousin, the Asian elephant is easily domesticated (驯化 ). The rare so-called white elephants have actually lent the authority of kingship to its rulers and until the 1920s the national flag was a white elephant on a red background. To the early Weste
24、rn visitors the countrys romantic name was “Land of the White Elephant“. Today, however, the story is very different. Out of work and out of land, the Thai elephant struggles for survival in a nation that no longer needs it. The elephant has found itself more or less abandoned by previous owners who
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