多选题 In 2007, Mother Jones published an article on "the ethanol effect," showing the negative ramifications of switching from foreign oil to corn-based ethanol. It pointed out that over just five years, the amount of corn used for ethanol had risen from 7 percent to 20 percent. That led to a rise in the price of corn, which in turn led to a rise in food prices. Since so much corn was used to manufacture ethanol, less was exported. This meant less corn on the global market and the potential of an increase in global hunger. Ironically, the production of corn requires a great deal of gasoline for tractors and harvesters, reducing the energy savings to below that of gasoline.

多选题 According to the passage, what are some negatives involved in switching from foreign oil to ethanol?

A、 The amount of corn needed means less corn available as food.
B、 It takes more and more corn to manufacture a single gallon of ethanol.
C、 Production of corn in general is surprisingly energy inefficient.

【正确答案】 A、C

【答案解析】Choose only those statements that are supported by the text. That leaves out choice B, which is never hinted at anywhere in the passage.

单选题 In the final sentence, the author suggests that

A、 using ethanol in place of gasoline does not ultimately save energy
B、 producing corn for ethanol rather than for food uses more energy
C、 retrofitting cars and tractors to run on ethanol is surprisingly costly
D、 farm equipment cannot be retrofitted to run on corn-based fuel
E、 gasoline is far more energy efficient than most people believe

【正确答案】 A

【答案解析】The author does not suggest that gasoline is energy efficient (choice F) but rather that ethanol is not, because its production uses lots of gasoline. The best answer is choice A.