GMAT逻辑题练习及答案(328)

2017-07-18 09:08

来源：新东方在线

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　　GMAT逻辑题目:

　　InAsia, where palm trees are non-native, the trees’ flowers have traditionallybeen pollinated by hand, which has kept palm fruit productivity unnaturallylow. When weevils known to be efficient pollinators of palm flowers wereintroduced into Asia in 1980, palm fruit productivity increased— by up to 50percent in some areas—but then decreased sharply in 1984.

　　Whichof the following statements, if true, would best explain the 1984 decrease inproductivity?

　　A. Prices for palm fruit fellbetween 1980 and 1984 following the rise in production and a concurrent fall indemand.

　　B. Imported trees are often moreproductive than native trees because the imported ones have left behind theirpests and diseases in their native lands.

　　C. Rapid increases in productivitytend to deplete trees of nutrients needed for the development of thefruitproducing female flowers.

　　D. weevil population in Asiaremained at approximately the same level between 1980 and 1984.

　　E. Prior to 1980 another speciesof insect pollinated the Asian palm trees, but not as efficiently as thespecies of weevil that was introduced in 1980.

　　GMAT逻辑答案:

　　Argument Construction

　　Situation

　　In 1980, the introduction of weevils to pollinate palms trees in Asia resulted in increased palm fruit productivity. This productivity decreased sharply in 1984.

　　Reasoning

　　What explains the sudden decrease in 1984? The palm trees had experienced a sudden burst of productivity beginning in 1980. What if an after-effect of that spurt was the cause? If that burst of productivity had used up the trees’ nutrients, then the trees would be unable to produce the flowers that are pollinated in order to produce fruit. This sudden exhaustion of the tree's resources is the best explanation for the sudden decrease in productivity. A. Falling prices and demand do not explain the falling productivity of the trees.

　　B. The lack of pests and diseases among imported trees does not explain the sharply decreased productivity.

　　C. Correct. This statement properly identifies a reason for sharply decreased productivity.

　　D. If the weevil population pollinating the trees remained the same, it is reasonable to think that productivity remained the same, so this does not explain the decrease.

　　E. A change that occurred before 1980 does not explain a change that occurred in 1984.

　　The correct answer is C.

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