【题目】A Brown University sleep researcher has some advice for people who run high schools: Don't start classes so early in the morning. It may not be that the students who nod off at their desks are lazy. And it may not be that their parents have failed to make sure bedtime. Instead, it may be that biologically these sleepyhead students aren't used to the early hour. "Maybe these kids are being asked to get up at the wrong time for their bodies, " says Mary Carskadon, a professor looking at problems of adolescent sleep at Brown's School of Medicine.

Carskadon is trying to understand more about the effects of early school time in adolescents. And , at a more basic level, she and her team are trying to learn more about how the biological changes of adolescence affect sleep needs and patterns. Carskadon says her work suggests that adolescents may need more sleep than they did at childhood, no less, as commonly thought. Sleep patterns change during adolescence, as any parent of an adolescent can prove. Most adolescents prefer to stay up later at night and sleep later in the morning. But it's not just a matter of choice—their bodies are going through a change of sleep patterns.

All of this makes the change from middle school to high school—which may start one hour earlier in the morning—all the more difficult, Carskadon says. With their increased need for sleep and their biological clocks set on the "sleep late, rise late" pattern, adolescents are up against difficulties when it comes to trying to be up by 5 or 6 a. m. for a 7: 30 a. m. first bell. A short sleep on a desktop may be their bodies' way of saying, "I need a timeout. "

1Carskadon suggests that high schools should not start classes so early in the morning because ________.

A. it is really tough for parents to ensure bedtime

B. students are so lazy that they don't like to go to school early

C. students work so late at night that they can't get up early

D. it is biologically difficult for students to rise early

2The underlined phrase "nod off"(Paragraph l) most probably means "________".

A. turn around B. agree with others

C. fall asleep D. refuse to work

3What might be a reason for the hard change from middle school to high school?

A. Adolescents depend more on their parents.

B. Adolescents need more sleep than they used to.

C. Adolescents sleep better than they did at childhood.

D. Adolescents have to choose their sleep patterns.

4What is the text mainly about?

A. Changes in adolescent sleep needs and patterns.

B. Problems in adolescent learning.

C. Adolescent sleep difficulties.

D. Adolescent heath care.

【题目】Do you drink water that's been left sitting out overnight or even for another day? Have you noticed it tastes different?

Tap water that has been left to sit out slowly begins to acquire an off taste. Many people think that this is because of microorganisms(微生物). But that's not what makes old water taste not fresh. For that we can thank carbon dioxide. After about 12 hours, tap water starts to go flat as carbon dioxide in the air starts to mix with the water in the glass, lowering its pH and giving it an off taste. But it's most likely safe to drink.

However, back to those microorganisms. If you use a dirty glass day after day, there is more of a chance of bacteria making themselves known; a risk that increases if you share the glass with another mouth as well. But assuming you use a fresh glass every few days, you probably won't have a problem unless the glass has been touched by dirty fingers, and especially if those dirty fingers went unwashed after using the bathroom.

As for plastic water bottles that have been left out in the sun or in the car, step away from the bottle, warns Dr. Kellogg Schwab, director of the Johns Hopkins University Water Institute. "A chemical called bisphenol-A, or BPA, along with other things used to make plastic can leach(过滤) into your water if the bottle heats up or sits in the sun," he explains. BPA, as you probably know, has been linked to everything from heart disease to cancer. Schwab also adds that plastic used for commercial bottled water isn't meant to be washed or refilled, so use only one time and recycle. Or don't buy them at all; use refillable water bottles instead.

1】Tap water begin to acquire an off taste because of ________.

A. BPAB. the glassC. the microorganismD. carbon dioxide

2According to Paragragh 2, tap water that's been left sitting out for 12 hours ________.

A. tastes betterB. is still safe to drink

C. contains few microorganismsD. is most likely undrinkable

3】What should we do with plastic water bottles that have been left out in the sun or in the car?

A. Throw them away.B. Refill them with fresh water.

C. Use them after they cool down.D. Clean them and use them again.

4】Which of the following is true about BPA?

A. It is safe for people to use.

B. It is a kind of new material.

C. It can cause great harm to people.

D. It is the main material to make plastic.

【题目】根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

It’s Nice to be Home

【1】 I have been fortunate enough to make trips to many countries.They were wonderful adventures filled with new sights and experiences.And my wife and I have another trip in the planning stages.

We're home now and have settled back into our daily routine of life.2 I find that when I am at home,particularly for a while when we have just returned from a trip,I feel very comfortable.Perhaps it is because everything around me is familiar and the daily routine is so much the same I can move through it almost without thinking.3Perhaps it is because we can have meals at home instead of always being in restaurants,although it's nice to let someone else do the cooking,and because I can sleep in my own bed.There are times I think it would be nice to simply stop travelling and stay home and I'm stile I would be very comfortable if that were to happen. 4

Yet I guess I am probably a restless soul because I know that after I have been home for a while I will start to think about other places we might go and other things we want to see.We will travel again and we feel fortunate to be able to do so.5 Still,one of the best things about travelling for me is coming home.I'm very comfortable here at home even if it is difficult to say exactly why.

A.I like to travel very much.

B.I enjoy local food while travelling.

C.I like being home,for whatever reason.

D.Perhaps it is because our friends are here.

E.And I enjoy my daily life at home so much.

F.We want to see as much of the world as we can.

G.Its lucky that my wife and I both love travelling.

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