Black holes not be seen directly, so determining the number of them is a tough task. A. can B. should C. must D. need 题目和参考答案——青夏教育精英家教网—

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Black holes _____ not be seen directly, so determining the number of them is a tough task.

A. can B. should C. must D. need

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A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

After the explosion gravity pulls in what’s left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so dense that a teaspoon of matter from it weighs billion of pounds.

The more the star shrinks, the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can go out. The star becomes black when there is no light. Then a black hole is born!

That’s what we know about black holes. What we don’t know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

But if the black hole doesn’t keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world．They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a “white hole” in a different universe. As the black hole swallows light, the white hole shines brightly — somewhere else. But where? A different place, perhaps, or a different time — many years in the past or future.

Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed．So far the time being, black hole must remain a mystery.

Black holes are a mystery—but that hasn’t stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth’s energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste—a sort of huge waste disposal (处理) in the sky!

When the star begins to die ______.

A．there is no fuel left in it B．its outer layer goes into space first

C．a huge explosion will happen D．it doesn’t give off light any longer

Which of the following doesn’t help produce a black hole?

A．The gravity inside the star is very strong.

B．The light can’t go out of the star.

C．The star becomes smaller and smaller

D．The dying star shines very brightly.

The black hole ______.

A．continues becoming smaller and smaller all the time

B．goes into another universe and becomes a white hole

C．can pull in everything we know of in the world

D．will appear at another place at a different time

What’s the best title for this passage?

A．A New Scientific Discovery: Black Holes

B．How Do Black Holes Come Into Being?

C．What Are Black Holes?

D．Travel Through A Black Hole

Astronomers and scientists think that a black hole is a region of space ______ which matter has fallen and _______ which nothing can escape.

A．into; from	B．towards; towards
C．out of; from	D．through; through

If you're one of the 13 million Americans still struggling to find a job, or wanting to change jobs, a lot of your applications are probably being swallowed up by the "the black hole．" That's when you send in a job application and never receive any follow-up from the company．In fact, only 25 out of 100 applications ever get looked at by companies．

Now, a remarkable new service is helping job seekers instantly track almost every application they submit so they actually know what's going on．It's called Start Wire． corn and it lets job seekers track their applications and find out whether or not their applications have been reviewed, dismissed, or are still being considered．

How does it work? When you fill out a job application via a company website, you'll typically get an auto confirmation email from the company, thanking you for applying．And then, the waiting begins．

Start Wire has linked to more than 5 , 600 employers across the country and receives online updates on job applications for every one of their members．By allowing you to connect your job hunt to your Facebook and Linkedin accounts, it can notify you if you have any connections with the company that you apply for ．

And, Start Wire is free to use! Because Start Wire is a completely ad-supported site, they don't need to charge job seekers to use it．

Most importantly, Start Wire keeps your information private．Your job search activity will never show up on a social network or search engine．Start Wire has become invaluable to over 55, 000 job seekers in a highly competitive job market．

If you're tired of your job search resulting in dead-end responses, take advantage of this free service and give yourself a huge advantage in the job marketplace．

Click here to put your information on an official list and reach an arrangement with Start Wire to use a free service it provides, and improve your chances of finding a good job quickly．

1.You can probably read the passage from ___________.

A．a newspaper B．a website C．a poster D．a magazine

2.If your job applications are being swallowed up, it means that ______．

A．your personal information has been stolen

B．your job applications are under consideration

C．you can not receive any reply from the company

D．you have to pay money to get your applications back

3.If you want to use Start Wire first you should ________.

A．make a call to the website B．get access to some employers

C．register an account without payment D．email the company you will apply to

4.The passage is mainly intended to______.

A．prove the advantages of Start Wire

B．attract more people to use Start Wire

C．teach people how to access Start Wire

D．provide key facts about unemployment

Astronomers and scientists think that a black hole is a region of space ______ which matter has fallen and _______ which nothing can escape.

A．into; from B．towards; towards

C．out of; from D．through; through

The theory he ____ about black hole isn’t understood by most of people.

A .put up B put down C put off D put forward

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