选择知识点

Cigarettes aren't just harmful when they're being smoked. Even when cigarette ends go out and are cold, new research has found they continue to give off harmful chemicals in the air. In the first 24 hours alone, scientists say a used cigarette end will produce 14 percent of the nicotine（尼古丁） that an actively burning cigarette would produce.
While most of these chemicals are released within a day of being put out, an analysis for the United States Food and Drug Administration （FDA） found the level of nicotine fell by just 50% five days later.
"I was absolutely surprised," says environmental engineer Dustin Poppendieck from the United States National Institute of Standards and Technology （NIST）. "The numbers are significant and could have important impacts when cigarette ends are dealt with indoors or in cars. While much attention has been paid to the health influence of first-hand, second-hand and now third-hand smoking, it is not the case when it comes to the actual cigarette end of the matter."
To measure emissions（排放） from this forgotten thing, Poppendieck and his team placed 2，100 cigarettes that were recently put out inside a special room. Once the ends were sealed away, the team measured eight chemicals commonly produced by cigarettes, four of which the FDA have their eye on for being harmful or potentially so.
After setting the room's temperature, the researchers tested how emissions changed under certain conditions. When the air temperature of the room was higher, for instance, they noticed the ends produced these chemicals at higher rates. This finding might discourage those who want to leave ashtrays（烟灰缸） out for days at a time, especially in the heat.



What do the researchers say about cigarette ends？ ______

A. They contain little nicotine.
B. They produce no nicotine 5 days later.
C. They give off nicotine for days.
D. They create as much nicotine as burning cigarettes.

What do Poppendieck's words suggest？ ______

A. First-hand smoking does most harm.
B. The findings are within his expectation.
C. Cigarettes should be dealt with indoors.
D. Health influence of cigarette ends is ignored.

Which word best describes the authors attitude to not cleaning ashtrays for days？ ______

A. Unclear.
B. Disapproving.
C. Unconcerned.
D. Puzzled.

What can be the best title for the text？ ______

A. Used Cigarette Ends Release Harmful Chemicals
B. Cigarettes Are More Harmful While Being Smoked
C. Research Found Reasons for Cigarette Ends' Harm
D. Cigarette Ends Produce More Chemicals in the Heat

Sure, chocolate is a delicious treat, and it's a staple of some of our favorite desserts. But it's not a health food, so it should be enjoyed in moderation-right？
Well, it turns out that eating chocolate might actually have a pretty significant health benefit. According to research conducted by five scientists in Italy, compounds found in chocolate, called flavanols, can help boost cognitive （认知的） performance. Yup, chocolate's good for your brain.
The scientists, studying at the Universities of Rome and L'Aquila, summarized research from ten different studies. The studies assessed people's performance on cognitive tests before and after eating cocoa or chocolate. The results were pretty telling： in nine out of the ten studies, there was a noticeable improvement after the subjects had eaten the chocolate. The scientists found improvements in "general cognition, attention, processing speed and working memory." Sounds pretty good to us!
And that's not all. In subjects, especially women, who performed the tests while sleep-deprived, the flavanols helped relieve the negative effects of the sleep deprivation. And there's even more good news. The researchers also found that eating chocolate daily （over periods ranging from five days to three months） produced noticeable long-term improvements in cognition. Older adults, whose memories were already declining, saw an especially significant improvement.
All chocolate has flavanols, since they occur naturally in cocoa. However, dark chocolate lovers feel happy, because it has more flavanols than any other type of chocolate. In fact, the scientists themselves have claimed that, after doing this research, they've started eating dark chocolate every day!
Now, we're not saying you should start eating chocolate for breakfast, lunch and dinner - it's still high in sugar and low in nutrients. But next time you find yourself yawning after a sleepless night, snack on some chocolate and let the flavanols work their magic.



What does the underlined phrase in Paragraph 1 probably mean？ ______

A. As much as possible.
B. For three meals.
C. In right amount.
D. Not in the least

How does a student perform while learning after eating chocolate？ ______

A. He memorizes less than before.
B. He can't concentrate on lessons in the slightest.
C. He becomes more excited.
D. He understands what the teacher says faster.

According to the passage, if your memory fails, what should you do？ ______

A. Eat chocolate as three meals.
B. Use chocolate as a daily snack.
C. Hunt for dark chocolate.
D. Ask a doctor for advice.

What's the main idea of the passage？ ______

A. Chocolate is a beneficial but unhealthy food.
B. Eating chocolate benefits our learning.
C. Eating chocolate works on your sleep.
D. Chocolate contains low nutrients.

People who grow up left-handed have a different, more flexible brain structure than those born to take life by the right hand, say researchers at the University of California, Los Angeles.
The reason is that right-handers have genes that force their brains into a slightly more one-sided structure, according to the research. Left-handers appear to be missing those genes.
"There really is a difference in brains that results in a more symmetric（对称的）brain in left-handers, where the two sides are more equal," said Daniel Geschwind, who led the research team.
In the effort to understand how the brain shapes the mind, researchers have been trying to document the way genes and environment affect intelligence and mental abilities. They found that right- and left-handedness is determined by genetics. If a person has the gene for right-handedness, that person will be right-handed. People who do not have that gene, however, can be either left- or right-handed. There is no specific gene for left-handedness.
Right-handers typically have a larger left brain, where their language abilities are concentrated. Conversely, left-handers have more balanced brains. The language abilities of left-handers more often are concentrated on the right side.
The UCLA researchers conducted brain scans on 72 pairs of male identical （同卵双生的） twins between 75 and 85 years old. They noticed that if identical twins carry the gene for hand preference, both must be right-handed. If they lack the gene, one twin can develop right-handed while the other can develop left- handed.
The researchers found that the brains of identical right-handed twins were very similar in size and structure. But when a left-hander was part of the twin set, the brains were different. The conclusion, researchers said, is that the absence of the gene for hand preference allows the brain to develop differently as the individual grows up.



What is the finding of the researchers of UCLA？ ______

A. Left-handers have more balanced brains.
B. Right-handers have more flexible brains.
C. Left-handers' brains are more one-sided.
D. Right-handers' brains are more symmetric.

Which element determines a person's hand preference？ ______

A. Environment.
B. Intelligence.
C. Habit.
D. Gene.

What can be said about identical twins？ ______

A. They always have similar brain structure.
B. They never carry the gene for hand preference.
C. They have different genes for hand preference.
D. They can have different hand preference.

What did the UCLA team research on？ ______

A. People's genetic makeup.
B. People's hand preference.
C. People's brain sizes.
D. People's communicative skills.

Attention to the fight against climate change tends to be focused on trees, but 75% of the planet's surface is covered by the ocean, and a natural process taking place underwater has excited scores of investors at the recent World Economic Forum who may want to help.
During the recent wildfires in the Amazon rainforest, journalists often described trees as the"lungs of the world"， but that title most certainly belongs to phytoplankton（浮游植物）， which alone refreshes nearly 50% of the atmospheric oxygen on planet earth, the value of four Amazons.
And, in the effort to stop the warming of the planet, our greatest assistants could belong to whales, because of the great amount of their excrement（粪便）left in the sea.
A new paper published by economist Dr. Ralph Chianti highlights the influence that whales, especially blue whales, and their excrement have on climate change. It is all due to whales' excrement in the diets of phytoplankton.
The tiny marine algae（海藻）floats at the center of several marine food webs, and they provide food for a host of sea creatures including whales, while also requiring whales' excrement to feed on. They also require CO₂to survive, just like trees.
Whales, after deep-sea dives for krill, return to the surface and release excrement, which is rich in nitrogen and iron, into the top ocean layer, which provides a key food source for phytoplankton.
In his paper, Dr. Chiami suggests that since phytoplankton populations expand wherever whales are,a significant effort should be made to fight against climate change by encouraging the growth and protection of whale populations. "At a minimum, even a 1% increase in phytoplankton productivity thanks to whale activity would capture hundreds of millions of tons of additional CO₂ a year, which is equal to the sudden appearance of 2 billion mature trees," says Chiami.



What makes the investors excited？ ______

A. Trees' function as "lungs of the world".
B. Phytoplankton's ability to create oxygen.
C. The success of the World Economic Forum.
D. People's continuous fight against climate change.

Why are whales called our assistants in fighting global warming？ ______

A. They refresh much oxygen.
B. They never send out CO₂.
C. They kill much phytoplankton.
D. They supply food to phytoplankton.

Which can best describe the relationship between phytoplankton and whales？ ______

A. Complex.
B. Competitive.
C. Interdependent.
D. Distant.

What does Chiami advise us to do？ ______

A. Rebuild food webs.
B. Try to protect whales.
C. Grow more phytoplankton.
D. Restrict population explosion.

If you attend the graduation ceremony in the future, you will have to be ________ dressed.（　　）

After several hours of discussion, I ______ him in accepting the project.

The earthquake took away his parents but with a strong will he finally ________.（　　）

Helen has been unable to concentrate on her lessons recently, which may ________ her poor result in the final exam.（　　）

That kind of ice-cream ________like a mixture of banana and strawberry is delicious.（　　）

We are going to lose anyway, but the ________ of playing is not to win but to participate.（　　）