7．It took 100years，but finally，scientists proved Albert Einstein's theory that gravitational waves exist．
The waves were predicted as part of Einstein's general theory of relativity nearly 100years ago．It was the theory of the physics behind the workings of our world and the universe．
The idea was that the waves are like ripples in space，caused by some of the violent and energetic processes in the universe．For example，two black holes crashing into each other．
Now a group of scientists，including ones from Caltech，MIT and the LIGO Scientific，Collaboration finally found the gravitational waves．
David Reitze is the executive director of the LIGO observatory at Caltech．
"We have detected gravitational waves．We did it!"
What are these gravitational waves？
Well，imagine throwing a rock into a pond．When the rock hits the flat surface of the water，it creates ripples or waves．Space-time is like the surface of the water．So that means gravitational waves are like the ripples moving out from where the rock hits the water．
It might be hard to understand，but those gravitational waves expand and contract space and time as they move through space．And when they get to the Earth，the waves pass through，and they contract and expand the planet as the waves go by．
It was Einstein who said these gravitational waves should be observable．
But these are not huge waves．They are very，very small，which is why it took so long to find them．You cannot see them with your eyes．They are smaller than the size of an atom．
How did the scientists find them？
They used a giant scientific tool called LIGO，which stands for the Laser Interferometer Gravitational-Wave Observatory．The billion-dollar LIGO project is two L-shaped observatories．One is in Louisiana and the other in Washington state．
For years，scientists have been watching two black holes in another faraway galaxy．The two were spinning around each other，moving closer and closer together．When they finally crashed into each other，it was with such power and force that gravitational waves rang throughout the universe，like a giant bell．
Those waves，traveling at the speed of light，finally reached the Earth，some l.3billion years later．They are the same waves that the scientists announced this past week．
So，what does this discovery mean？
Our understanding of the heavens changed dramatically．
32．What are gravitational waves about？A
A．About the workings of the universe．
B．About how black holes form．
C．About how the universe began．
D．About how the ripples form on the surface of water．
33．The underlined sentence"two black holes crashing into each other"is intended to expressB．
A．how the universe begins to exist
B．how gravitational waves form
C．how new black holes appear
D．how the earth is affected
34．Why are gravitational waves difficult to detect？A
A．Because they are too small．
B．Because they are far away．
C．Because they seldom occur．
D．Because they have disappeared．
35．With the discovery of gravitational waves，we'llC．
A．create a new world
B．make full use of gravitational waves
C．view the universe in a new way
D．avoid being hit by black holes．
分析 本文报道了最近发现的引力波．文章详细介绍了引力波的产生，引力波发现的意义和引力波的寻找过程．
解答 32．A．细节理解题．根据文章"The idea was that the waves are like ripples in space，caused by some of the violent and energetic processes in the universe"可知，引力波是宇宙的一些剧烈运动．故选A．
33．B．推理预测题．前文讲到引力波是由宇宙中的剧烈运动所产生的．则紧接着举的划线部分黑洞的例子，也是在证实这一观点．故选B．
34．A．细节理解题．根据文章"They are very，very small，which is why it took so long to find them．"可知，引力波非常小，以至于这么久才发现它．故选A．
35．C．细节理解题．根据文章"So，what does this discovery mean？Our understanding of the heavens changed dramatically"可知，引力波的发现让我们对宇宙的思考又发生了变化．故选C．
点评 本文为新闻报道类阅读．新闻报道类在英语阅读理解中是一种特点十分鲜明的题材．因为文章往往呈现出"倒金字塔"的特征，此类题的英语阅读理解技巧是重点看导语．导语位于新闻报道的首段，高度概括新闻事实，通过它点出新闻的主题，其次寻找关键词，理解题意，做出解答．
提分百分百检测卷单元期末测试卷系列答案
小学期末标准试卷系列答案