21、 Carbon nanotubes are currently the most popular topic in material science.

A．Right

B．Wrong

C．Not mentioned

22、It is indicated that materials stronger than natural silk can be expected in the future.

A．Right

B．Wrong

C．Not mentioned

下面的短文后有2項(xiàng)測試任務(wù)：(1)第23—26題要求從所給的6個(gè)選項(xiàng)中為指定段落每段選擇1個(gè)標(biāo)題；(2)第27-30題要求從所給的6個(gè)選項(xiàng)中為每個(gè)句子確定一個(gè)最佳選項(xiàng)。

23、根據(jù)材料，回答23-31問題。

Black Holes

1. Black holes can be best described as a sort of vacuum, sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars. Stars thatare near death can no longer burn due to loss of fuel, and because its temperature can nolonger control the gravitational ( 重力的) force, hydrogen ends up putting pressure onto thestar's surface until it suddenly explodes then collapses.

2. Black holes come from stars that are made of hydrogen, other gases and a few metals. Whenthese explode it can turn into a stellar-mass (恒星質(zhì)量) black hole, which can only occurif the star is large enough (should be bigger than the sun) for the explosion to break it intopieces, and the gravity starts to compact every piece into the tiniest particle. Try to see andcompare: if a star that's ten times the size of the sun end up being a black hole that's no longer than 70 kilometers, then the Earth would become black hole that's only a fraction ofan inch !

3. Objects that get sucked in a black hole will always remain there, never to break free. Butremember that black holes can only gobble up (吞噬) objects within a specific distance toit. It's possible for a large star near the sun to become a black hole, but the sun willcontinue to stay in place. Orbits (軌道) do not change because the newly formed blackhole contains exactly the same amount of mass as when it was a star, only this mass istotally contracted that it can end up as no bigger than a state.

4. So far, astronomers have figured out that black holes exist because of Albert Einstein'stheory of relativity. In the end, through numerous studies, they have discovered that blackholes truly exist. Since black holes trap light and do not give off light, it is not possible todetect black holes via a telescope. But astronomers continue to explore galaxies (銀河系),space and the solar system to understand how black holes work. It is possible that black holescan exist for millions of years, and later contribute further process in galaxies, which caneventually lead to creation of new entities. Scientists also credit black holes as helpful inlearning how galaxies began to form.

Paragraph 1__________

A．Is there proof that black holes really exist?

B．What are different types of black holes?

C．How are black holes formed?

D．How were black holes named?

E．What happens to the objects around a black hole?

F．What are black holes made of?

24、 Paragraph 2__________

A．Is there proof that black holes really exist?

B．What are different types of black holes?

C．How are black holes formed?

D．How were black holes named?

E．What happens to the objects around a black hole?

F．What are black holes made of?

25、 Paragraph 3__________

A．Is there proof that black holes really exist?

B．What are different types of black holes?

C．How are black holes formed?

D．How were black holes named?

E．What happens to the objects around a black hole?

F．What are black holes made of?

26、 Paragraph 4__________

A．Is there proof that black holes really exist?

B．What are different types of black holes?

C．How are black holes formed?

D．How were black holes named?

E．What happens to the objects around a black hole?

F．What are black holes made of?

27、 Black holes are formed after__________

A．the creation of new entities

B．a(chǎn)n explosion of huge stars

C．the tiniest particle

D．the same amount of mass

E．the existence of black holes

F．a(chǎn) fraction of an inch

28、 When a large star explodes, the gravity compacts ever piece into_________

A．the creation of new entities

B．a(chǎn)n explosion of huge stars

C．the tiniest particle

D．the same amount of mass

E．the existence of black holes

F．a(chǎn) fraction of an inch

29、 A newly formed black hole and the star it comes from are of__________

A．the creation of new entities

B．a(chǎn)n explosion of huge stars

C．the tiniest particle

D．the same amount of mass

E．the existence of black holes

F．a(chǎn) fraction of an inch

30、 Albert Einstein's theory of relativity helps to prove__________

A．the creation of new entities

B．a(chǎn)n explosion of huge stars

C．the tiniest particle

D．the same amount of mass

E．the existence of black holes

F．a(chǎn) fraction of an inch

下面有3篇短文，每篇短文后有5道題。請根據(jù)短文內(nèi)容，為每題確定l個(gè)最佳選項(xiàng)。

31、根據(jù)材料，回答31-36問題。

Forecasting Methods

There are several different methods that can be used to create a forecast. The methodforecaster chooses depends upon the experience of the forecaster, the amount of informationavailable to the forecaster, the level of difficulty that the forecast situation presents, and thedegree of accuracy or confidence needed in the forecast.

The first of these methods is the persistence method; the simplest way of producing aforecast. The persistence method assumes that the conditions at the time of the forecast will notchange. For example, if it is sunny and 87 degree today, the persistence method predicts that itwill be sunny and 87 degree tomorrow. If two inches of rain fell today, the persistence methodwould predict two inches of rain for tomorrow. However, if weather conditions changesignificantly from day to day, the persistence method usually breaks down and is not the bestforecasting method to use.

The trends method involves determining the speed and direction of movement for fronts,high and low pressure centers, and areas of clouds and precipitation. Using this information, theforecaster can predict where he or she expects those features to be at some future time. Forexample, if a storm system is 1,000 miles west of your location and moving to the east at 250miles per day, suing the trends method you would predict it to arrive in your area in 4 days. Thetrends method works well when systems continue to move at the same speed in the samedirection for a long period of time. If they slow down, speed up, change intensity, or changedirection, the trends forecast will probably not work as well.

The climatology method is another simple way of producing a forecast. This methodinvolves averaging weather statistics accumulated over many years to make the forecast. Forexample, if you were using the climatology method to predict the weather for New York City onJuly 4th, you would go through all the weather data that has been recorded for every July 4thand take an average. The climatology method only works well when the weather pattern issimilar to that expected for the chosen time of year. if the pattern is quite unusual for the giventime of year, the climatology method will often fail.

The analog method is a slightly more complicated method of producing a forecast. Itinvolves examining today's forecast scenario and remembering a day in the past when theweather scenario looked very similar ( an analog). The forecaster would predict that the weatherin this forecast will behave the same as it did in the past. The analog method is difficult to usebecause it is virtually impossible to find a predict analog. Various weather features rarely align themselves in the same locations they were in the previous time. Even small differences betweenthe current time andre analog can lead to very different results.

Which of the following is NOT mentioned in choosing a forecasting method__________?

A．Necessary amount of information.

B．Degree of difficulty involved in forecasting.

C．Practical knowledge of the forecaster.

D．Creativity of the forecaster.

32、 The persistence method fails to work well when__________

A．it is rainy

B．it is sunny

C．weather conditions stay stable

D．weather conditions change greatly

33、 The trends method works well when

A．weather features are constant for a long period of time

B．weather features are defined well enough

C．predictions on precipitation are accurate

D．the speed and direction of movement are predictable

34、 The analog method should not be used in making a weather forecast when__________

A．the analog looks complicated

B．the current weather scenario is different from the analog

C．the analog is more than 10 years old

D．the current weather scenario is exactly the same as the analog

35、 Historical weather data are necessary in__________

A．the persistence method and the trends method

B．the trends method and the climatology method

C．the climatology method and the analog method

D．the persistence method and the analog method