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单选题

A．The global crop production remained about the same.
B．Rice had the same yields as soybean around the world.
C．The wheat and corn production decreased everywhere.
D．Rice and soybean yields kept balanced around the world.

参考答案D

解析:
A new study says climate change has reduced the world's wheat and corn production．(20-1) The study says rice and soybean yields have also decreased in some places--but increased in others．In the words of the researchers: (20-2) "For soybeans and rice, winners and losers largely balanced out．"
The researchers studied climate trends and global crop production between 1980 and 2008.
(21) They found that climate changes "are already exerting a considerable drag on yield growth" and may have affected food prices.
The study used computer models linking crop yields to weather．The researchers compared the results to what the yields might have been without climate changes．They found that corn production decreased by almost four percent and wheat production decreased by 5.5 percent.
Warming temperatures were reported in almost all of Europe, much of Asia and some of South America and Africa．During the study period most countries had greater temperature changes from year to year than they have had historically．But the study says the United States was an important exception--at least so far.
Corn and wheat yields in most of North America remained about the same．Russia's wheat yields decreased the most．The largest loss in corn yields were in India and Brazil.
Wolfram Schlenkerj, one of the researchers, says the report can serve as a planning tool for policy makers．(22) If they are worried about rising food prices, it might be good to conduct some research
about breeding for heat tolerance and maybe even drought tolerance.
Why do researchers say "winners and losers largely balanced out"?

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A．Corn production decreased by 4.5 percent．
B．Rice production increased by 5.5 percent．
C．The crop yield growth slowed down.
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单选题

A．They might encourage the research of heat tolerance crop.
B．They should take measures to control the rising food price.
C．They should put more effort on growing rice and soybean.
D．They are supposed to give up growing corn and wheat.

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A．More men felt great stress and pressure than women.
B．The survey is conducted among high school students.
C．The percentage of students feeling overwhelmed is decreasing.
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