每日一题

Writing & Language

After reading the passage, choose the answer to the question that most effectively improves the quality of writing in the passage or that makes the passage conform to the conventions of standard written English. Sometimes the question will include a "NO CHANGE" option. Choose that option if you think the best choice is to leave the relevant portion of the passage as it is.

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 Chuck Maynard to restore North America's population of American chestnut trees, which was decimated in the early 1900s by a fungus known as chestnut blight. A fungus, C. parasitica, contributes to the growth of cankers on the trees' trunks; these cankers, in turn, prevent trees from transporting water from their roots to their branches and leaves. To render American chestnut trees resistant to the blight, Powell and Maynard experimented with altering the genetic makeup of the trees. The resultant genetically engineered trees are called Darling 4 American chestnut trees, and during the first 15 weeks after infection with chestnut blight, they grow cankers that are much smaller than those that grow on American chestnut trees.

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