Scientists didn’t know much about lung cancer _____.

A.didn't achieve

B.wasn't able to achieve

C.wouldn't have achieved

D.shouldn't have achieved

Danny didn't say anything about the matter to Mrs. Green because______.

A. she had known it

B. the other boys told her

C. he didn't want to be in trouble

D. his mother didn't want him to say it

11. A. what be studied B. what should study C. what to study D. what studied

12. A. In three years B. For three years C. After three years D. Three years

13. A. never would be B. would be never C. would not be ever D. would never be

14. A. I didn't either B. Nor I did C. So didn't I D. Also didn't I

15. A. Not al1 B. Neither C. Nor D. Both

16. A. since B. while C. before D. whereas

17. A. understand B. recognize C. suggest D. inform

18. A. speaking B. to say C. to speak D. saying

19. A. a lot B. much C. a bit D. more

20. A. as B. being C. to be D. but

(判断)AIDS, fifty years ago, didn’t exist.Fifteen years ago a few doctors and public health officials noticed the first cases.Within a few years it was clear that it has now killed almost 14 million people around the world.

Four years ago doctors came up with the first treatment to make a dent in the spiraling death rate.Today that treatment works for some patients, but it’s not clear how long results will last.And still there is no cure.

For the nearly 35 million people around the world now living with HIV, there may never be a cure.Once cells are infected with HIV, it is very difficult — perhaps impossible ―to rid them of the virus.The only sure way to stop AIDS is to prevent infection in the first place, and only a vaccine can do that.

Unfortunately HIV is one of the most changeable viruses known to science.After more than a dozen years, it is still rather difficult to produce effective vaccine.

Still the billions of dollars spent on AIDS research over the past 20 years has not been wasted.As scientists learn more about how HIV survives in the human body, they are realizing that drugs alone may not be enough.To contain the virus effectively, it may take a balance between drug treatments that can keep HIV levels low and a strengthened immune system that can then target and destroy the remaining virus.Until scientists find a vaccine, however, they may control but never cure the century’s final scourge.

46.AIDS didn’t exist fifteen years ago.

47.Scientists have found a vaccine which can prevent HIV infection.

48.Although some treatment works for some patients with HIV, there is still no cure.

49.HIV is a changeable virus so that it is very difficult to produce effective vaccine.

50.We have wasted billions of dollars on AIDS research.

1、In the past，people didn’t think about the future very much because life was boring.()

2、Life in the future will be a little different from today's life.()

3、It's impossible for people to go on holiday to the moon.()

4、Meat will be more expensive in the future.()

5、People will live longer than people do now.()

The critical issue facing the scientists is to _____.

［A］ apply the newly-found knowledge to the benefit of mankind

［B］ end their horse race for the success of science

［C］ get down to their genome research

［D］ set their differences aside

But if you're unhappy, it can't do you any good to smile, can it？ Not true. Apparently, the positive effects of smiling are just the same whether you feel like smiling or not. Scientists in California asked a group of actors to act five different feelings; happiness, sadness, anger, surprise and fear—just using their faces. Changes in their heart rate, blood pressure and temperature were written down. Most of the feelings they acted didn't cause changes, but when the actors smiled, their heart rate and their blood pressure went down. This happened to make them feel better.

A sense of humor also helps to keep things in perspective. Interfering friends or a flat tire won't seem quite so bad if you can see the funny side. So if you find yourself in a stressful situation, try to imagine how it must seem to an outsider with a sense of humor and let yourself laugh. A psychologist writes, " If people try to show a positive reaction instead of a negative one, this will eventually become part of their personality. If you start to laugh, in time you will actually become happier.

How do people differ from other animals？

A. But Komfeld said scientists will not know about the applicability of the drugs in humans until a similar study is done on humans. “What’s very encouraging is that these drugs were developed to treat humans, and they are well understood, because they’ve been used for a long time, ” he said。

B. Later the scientists discovered that two related anticonvulsant drugs also lengthened the lives of the worms-in the case of one drug, by almost 50 percent. “This was a big surprise to use, Komfeld said. ”“We didn’t think anticonvulsant drugs had any particular relationship to aging. That connection was completely unexpected. ”

C. Roundworms are a poor subject for experiments, because they are not like humans, even though their molecules are similar. For example, they have no bones, nor do they show emotions, making it difficult to know how exactly human subjects would react to these drugs in large quantities. However, using the worms allows experiments to be conducted quickly, because they do not live for long。

D. “Somehow the neural activity seems to regulate the aging of all of the body the skin, musculature, and reproductive tract, ” Kornfeld said. “Somehow the nervous system coordinates the progress of all these tissues, evidently, though the life stages. But we don’t know how it does that. ”

E. The discovery may also shed light on the little-understood aging process. Since the drugs act on the neuromuscular systems of both humans and worms, the findings hint at a link between neural activity and aging。

F. Unlike vertebrates, the worms are ideal subjects for the study of aging because of their short life spans, which last only a couple of weeks in a laboratory. The worm is well known in genetics, and the worm’s genome has been sequenced。

G. Use of this drug has been permitted by law since 1998 and wider use is now expected as a result of the studies. “We can clearly link this drug with human aging, but we still need to find proof, says Kornfeld optimistically. ”

选词填空：The method for making beer has changed over time. Hops (啤酒花)，for example, which many a modern beerits bitter flavor, are a 26 recent additions to the beverage. Thiswas mentioned in reference to brewing in the ninth century. Now, researchershave found a 27 ingredient in residue (残留物) from 5000-year-old beer brewingequipment. While excavating two pits at a site in thecentral plains of China, scientists discovered pottery fragments from pots,funnels, amphorae, and stoves (stove fragment pictured). The different shapesof the containers 28 theywere used to brew, filter, and store beer—they may be ancient “beer-making tools,” and the earliest 29 evidence of beer brewing in China, the researchers report online today in theProceedings of the National Academy of Sciences.To30 thathypothesis, the team examined the yellowish, dried 31 insidethe vessels. The majority of the grains—about 80%—were from cereal cropslike barley (大麦), andabout 10% were bits of roots, 32 lily,which would have sweetened the brew, the scientists say. Barley was anunexpected find: The crop was domesticated in western Eurasia and didn’t becomea 33 food incentral China until about 2000 years ago, according to the researchers. basedon that timing, they suggest barley may have 34 in theregion not as food, but as 35 material forbeerbrewing.

A) arrived

B) consuming

C) direct

D) exclusively

E) including

F) inform

G) raw

H) reached

I) relatively

J) remains

K) resources

L) staple

M) suggest

N) surprising

O) test