托业考试即TOEIC（Test of English for International Communication），中文译为国际交流英语考试，是针对在国际工作环境中使用英语交流的人们而指定的英语能力测评，由美国教育考试服务中心计。由于TOEIC考试运用于商业环境, 亦被工商界使用，在国际上历经二十余年的品牌锤炼后已被视为国际标准，因此又有“商业托福”之称。全球已有60多个国家的超过9000家国际企业使用了“托业”标准，近年就有超过500万人次应试。因此考试的难度也越来越有所增加。为了帮助大家顺利的通过托业考试，考8托业考试网为大家精选了大量的辅导资料和练习题集，欢迎大家前来我站学习。

What Do They Do?

　　1、Read the patterns of wide and narrow rings in wood from different trees. They match patterns from different trees to identify the year that a tree produced a particular ring. This process of matching across specimens is "cross-dating."

　　2、Estimate archaeological ages. Andrew Ellicott Douglas was the first dendrochronologist. He became famous for his studies of Pueblo ruins, which he analyzed by cross-dating, the tool that he developed as his "key to prehistoric chronology."

　　3、Predict future drought, flood, and other conditions. A. E. Douglas proposed that tree rings would be allow us to measure past climate and, potentially, to predict drought and flood over a period of years, which would provide economic advantage.

　　What Causes Variations in Tree Rings?

　　When conditions encourage growth, a tree adds extra tissue and produces a thick ring. In a discouraging year, growth is slowed and the tree produces a thin ring. Much of the variation in tree rings is due to variations year-to-year in:

　　1、Higher springtime temperature. If spring starts early, the growing season is likely to be longer than usual, causing a tree to have a wider ring.

　　2、Lower springtime temperature. A late spring is likely to shorten the growing season, causing a tree to have a narrower tree ring.

　　3、Abundant rainfall increases growth, producing a wider ring.

　　4、Drought decreases growth, producing a narrower ring.

　　5、Species of tree do differ in their response to weather changes. One might respond strongly to changes in overall rainfall, another might be more sensitive to the amount of rain during the late summer, and another to a temperature change that alters the length of the growing season.

　　6、Crowding from neighboring trees. This causes a series of narrow rings. Crowding is suspected when the series of narrow rings is more than three, because droughts are usually only one to three years.

　　7、If the rings are narrow on one side of a tree with wide rings on the other, the tree was crowded on the side of the tree where the rings are narrow.

　　8、A series of many narrow rings followed immediately by wide rings probably means that an encroaching neighbor died, releasing the crowded tree into a growth spurt.

　　9、Fire scars suggest past forest fires. The number of annual rings between fire scars shows the period between fires.

　　10、Scars due to insect plagues indicate insect infestations.


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