新SAT官方Daily Practice每日一题写作题

Some plant pathologists have turned to genetic engineering to devise new ways of responding to botanical diseases. Plant pathologist William Powell,for instance, teamed up with forest biologist ChuckMaynard to restore North America's population ofAmerican chestnut trees, which was decimated in theearly 1900s by a fungus known as chestnut blight. A fungus, C. parasitica, contributes to thegrowth of cankers on the trees' trunks; these cankers, in turn, prevent a tree fromtransporting water from their roots to their branches and leaves. To render American chestnuttrees resistant to the blight, Powell and Maynard experimented with altering the geneticmakeup of the trees. The resultant genetically engineered trees are called Darling 4 Americanchestnut trees, and during the first 15 weeks after infection with chestnut blight, they growcankers that are much smaller than those that grow on American chestnut trees.

A.NO CHANGE

B.trees

C.that tree

D.it

重点单词：

prevent [pri'vent]v. 预防，防止

population [.pɔpju'leiʃən]n. 人口 ，(全体)居民，人数

devise [di'vaiz]vt. 设计，发明，遗赠给 n. 遗赠

fungus ['fʌŋgəs]n. 真菌，霉菌 (复数为funguses或fungi)

resistant [ri'zistənt]adj. 抵抗的，反抗的n. 抵抗者

render ['rendə]vt. 使成为，提供，报答，着色; 执行，实施

genetically [dʒe'netikəli]adv. 遗传(基因)方面

restore [ri'stɔ:]vt. 恢复，修复，使复原

consistent [kən'sistənt]adj. 始终如一的，一致的，坚持的

infection [in'fekʃən]n. 传染，影响，传染病

答案：B

解析：

Choice B is the best answer because it maintainsagreement between the plural noun "trees" and theplural pronoun "their." This choice is also consistentwith the first part of the sentence's use of plural trees.