题目内容：

Scientists announced that they had found the gravitational waves（引力波）that confirmed a prediction made by Albert Einstein a century ago.The discovery,made with the Laser Interferometer Gravitational—Wave Observatory, known as LIGO,is the milestone（里程碑）in a decades—long search for signs of this phenomenon."The discovery will open a new window onto the universe,"said David Reitze,executive director of LIGO.

Since humans first watched skyward,we have relied on light of all wavelengths to describe the universe.The light that could be seen first showed the starry heavens,while infrared（红外线的）waves allowed us to see older and more distant stars.

But now,researchers will be able to sense the universe in a whole new way: with their "ears"."We can hear gravitational waves.We can hear the universe,"Gabriela Gonzalez,LIGO's spokeswoman at Louisiana State University,said."That's one of the beautiful things about this: We are not only going to be seeing the universe,we are going to be listening to it."

Gravitational waves,which Einstein predicted as part of his general theory of relativity,occur as objects accelerate or decelerate through space,much the way a boat moving on a lake sends waves across the water's surface. But they're so tiny that until now it's been nearly impossible to find them,even those caused by something as large as a planet moving around the sun.

To pick up this signal,scientists have to look for violent events in the universe.This particular signal appears to have been caused by a collision.That occurred about 1.3 billion years ago between two black holes,holding 29 and 36 solar masses（太阳质量）.

Fiona Harrison,chair of Caltesh's division of physics,mathematics and astronomy,guessed that hundreds of new events would be found over the next few years,allowing scientists to perform a range of different types of studies. "There are probably many events we haven't dreamed of and this is just the beginning,"she said.

1.Why did Gabriela Gonzalez think LIGO's discovery important?

A. It confirmed Einstein's scientific prediction.

B. It allowed scientists to see more distant stars.

C. It changed traditional ideas about the universe.

D. It offered different way to study the universe.

2.It's hard to find gravitational waves because they     .

A. are too far to be felt

B. are too weak to be observed

C. are disturbed bu other planets

D. disappear soon after they happen

3.Which of the following would scientists consider to be a violent event?

A. Hearing the universe.

B. Searching for infrared waves.

C. A collision between black waves.

D. A planet moving around the sun.

4.It can be concluded that     .

A. gravitational waves also exist in objects at rest

B. there's a long way to go in studying the universe.

C. gravitational waves show the beginning of the universe.

D. scientists began studying gravitational waves in recent years.