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题库 / Prep2012-CR-30
In preparation for a large-scale tree-planting project, Thomasville has recorded the location, species, and condition of every tree in its downtown area. The results will be compared with results of the last such tree census, taken 20 years ago. Planting trees primarily from the species that turns out to have the best record of survival will assure downtown Thomasville of an abundant tree population 20 years from now.
Which of the following, if true, most seriously undermines the claim that the tree-planting proposal will assure an abundant tree population?
Because of strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.
Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown.
A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period.
Very few species of trees grow as well in urban conditions as in natural conditions.
A city with a high proportion of any one species of trees can have its tree population devastated by one outbreak of a disease.
将现在的树木品种，数量，位置和20年前的树木的数据比较，选有着最佳生存记录的树木种植在市中心将会保证在未来有着大量的树木。问weaken
choice b, Thomasville有可靠的记录显示已经存活了20年以上的树木被砍伐，为了市中心的建设。irrelevant，过去的情况不能够类比到现在，不能说因为过去发生过，所以未来还会再发生。
choice e, 一个有着特别高比例的某种树的城市，可能会因为遭受一场疾病而导致树木全部毁灭。correct，方案的副作用
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