西安石油大学外语系：《大学英语 College English》精品课程教学资源（四级阅读题库）检索（4级）

In the early days of sea seamen on long voyages lived exclusively on salted meat and biscuits of them died of scurvy(坏血病), a disease of the blood which causes swollen gums, livid white spots on the flesh and general exhaustion. On one occasion in 1535, an English ship arrived in Newfoundland with its crew desperately ill. The mens lives were saved by Iroquois Indians who gave them vegetable leaves to eat. Gradually it came to

It is hard to get any agreement on the accurate meaning of the term \social class\. In everyday life, people tend to have a different approach to those they consider their equals from that which they assume with people they consid er higher or lower than themselves in the social scale. The criteria we use to“place new acquaintance(熟人), however, are complex mixture of factors. Dress, way of speaking, area of residence in a given city or province

1 Crime has its own cycles, magazine some years ago. Police records that were studied for five years from over 2,400 cities and towns show a surprising link between changes in the seasons and crime patterns. July and August,as do rape and other violent attacks. Murder,moreover, is more than seasonal it is a weekend crime. It is also a nighttime crime: 62 percent of murders are

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 subtraction of water from the ocean by means of evaporation-conversion of liquid water to water vapour. 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; this, by the way,is how much of the table salt we use is actually obtained

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