阅读理解训练（5）
阅读下列四篇短文，从每小题后所给的A,B,C或D四个选项中，选出最佳选项。
Rivers may be a significant source of the greenhou gas nitrous oxide (一氧化二氮), scientists now find.
Their calculation suggests that across the globe the waterways contribute three times the amount of nitrous oxide to the atmosphere as had been estimated by the International Panel on Climate Change (IPCC), the United Nations scientific body charged with reviewing climate change rearch. They found that the amount of nitrous oxide produced in streams is related to human activities that relea nitrogen (氮) into the environment, such as fertilizer u and wage discharges.
“Human activities, including fossil fuel combustion and intensive agriculture, have incread the availability of nitrogen in the environment,” said Jake Beaulieu of the University of Notre Dame and the U.S. Environmental Protection Agency in , , and lead author of the paper published this week in the journal Proceedings of the National Academy of Sciences.
“Much of this nitrogen is transported into river and stream networks,” Beaulieu said. There, microbes (微生物) convert the nitrogen into nitrous oxide (also called laughing gas) and an inert gas called dinitrogen (二氮).
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The finding is important, the rearchers say, becau nitrous oxide is a powerful greenhou gas that contributes to climate change and destruction of the stratosphere’s ozone layer, which protects us from the sun’s harmful ultraviolet (紫外线) radiation. Compared with carbon dioxide, nitrous oxide is 300-fold more powerful in te
rms of its warming potential, though carbon dioxide is a far more common greenhou gas. Scientists estimate nitrous oxide accounts for about 6 percent of human-induced climate change.
Beaulieu and colleagues measured nitrous oxide production rates in 72 streams. When summed across the globe, the results showed rivers and streams are the source of at least 10 percent of human-caud nitrous oxide emissions to the atmosphere.
“Changes in agricultural and land-u practices that result in less nitrogen being delivered to streams would reduce nitrous oxide emissions from river networks,” Beaulieu said.
1. From the cond paragraph we can learn .
A. actually rivers give off much more nitrous oxide than expected
B. scientists’ calculation is totally wrong
C. human activities relea nitrous oxide in to the rivers
D. there is no nitrogen in fertilizer
2. Which of the following is NOT the source of nitrogen?
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A. Fertilizer u. B. Sewage discharges. 阿昌族
C. Fossil fuel combustion. D. Climate change.
3. Nitrous oxide is a powerful greenhou gas becau .
A. it can protect us from the sun’s harmful ultraviolet radiation
B. it is to blame for most of human-induced climate change
C. it is a far more common greenhou gas胡旋
D. it has much more warming potential than carbon dioxide
4. What does the passage mainly tells us?
A. Rivers may be a source of the greenhou gas nitrous oxide.
B. It’s human activities that relea nitrogen into the environment.
C. How to reduce nitrous oxide emissions from river networks
D What to do with the climate change caud by nitrous oxide. 晓晓学堂
【参考答案】1—4、ADDA
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A
When I was 11, I threw a glance into Dad’s lunch box and made the unexpected discovery that my mother still showed her love towards my father. The evidence, a napkin resting on top of the sandwiches packed in wax paper, was certain “Love you!” she had written on the napkin. “ Meat loaf for supper!”
Mom penned all kinds of messages to Dad on tho paper napkins, and he saved a whole pile of them. What embarrasd me as a kid has become a precious memory of my parents.
It also started my own brand of lunch box notes. When my kids were young, I’d glue little drawings on their lunches. Lots of sketches(素描) of our dog, Max, along with smiling flowers. When they were teenagers, I’d copy words of wisdom from great people, Einstein, for example, or Bruce Springsteen. Then, my kids grew up making their own handwritten notes. And my husband writes me love notes on recycled paper, becau he’s all about being green.
Friends who know about my lunch box notes eagerly share stories of their own family traditions. So many focus on food. Maura’s mom always drew hearts on the shells of hard-boiled eggs. Melinda wrote messages on her kids’ bananas.
We’re into the third generation of lunch box notes in our home. Whenever my 3-year-old grandson, Clayton, spends the night, he knows his lunch is going to have a napkin note from Grandma in the morning. Last week, I drew a picture of me, waving widely and shouting his name. He took one look at it and screamed, “ Where’s Grandpa?” I added a man in a clean shirt. “ You forgot his tie,” he said. I quickly drew a line of stripes(条纹) down the front of the shirt. Clayton smiled. “Grandpa,” he whispered, running his fingers across the napkin. “It’s you!”
21. When the author first saw Dad’s lunch box notes, she felt ______.
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