Since people first sent rockets into space in the 1950s, we have been leaving behind all sorts of things. Some of them, like the camera, were lost by astronauts while they did work outside their spaceship. But much of the space junk is made up of little pieces of things that were once bigger objects, until they struck each other and broke apart.
Some things we send into space fall back toward the earth and burn up in the atmosphere. But larger pieces sometimes survive the extreme heat and hit the ground or the ocean at great speeds. So there is always concern that something may fall from the sky and do some harm.
But space junk falling on housetops (屋顶) is not the biggest worry. Scientists are concerned about what happens when an empty rocket strikes another while orbiting (绕轨道飞行) the earth. Two big things become many smaller things. They then hit other things. The pieces get smaller and smaller until they form a cloud of junk that blocks the path of future space vehicles.
So what can be done to clean up the space around our planet? Marco Castronuovo, an Italian researcher, talks about sending a satellite into space that would get very close to some of the larger pieces of space junk. The satellite would connect a small rocket to the useless object. When the rocket explodes, it pushes the junk into a lower and slower orbit, nearer the earth. After a time, the junk burns up in the atmosphere.
Mr. Castronuovo has proposed (提议) using a number of small satellites with robotic arms. One arm would catch the space junk, and another arm would connect the rocket. He imagines that each satellite would jump from one large piece of junk to another. He thinks this method could destroy about ten large objects each year.
Scientists have been concerned about space junk for many years. Right now, the costs of the clean-up have been too great. Mr. Castronuovo says his system could be put in place for a much more reasonable amount of money.
【小题1】Much of the space junk _____.

Since people first sent rockets into space in the 1950s, we have been leaving behind all sorts of things. Some of them, like the camera, were lost by astronauts while they did work outside their spaceship. But much of the space junk is made up of little pieces of things that were once bigger objects, until they struck each other and broke apart.

Some things we send into space fall back toward the earth and burn up in the atmosphere. But larger pieces sometimes survive the extreme heat and hit the ground or the ocean at great speeds. So there is always concern that something may fall from the sky and do some harm.

But space junk falling on housetops (屋顶) is not the biggest worry. Scientists are concerned about what happens when an empty rocket strikes another while orbiting (绕轨道飞行) the earth. Two big things become many smaller things. They then hit other things. The pieces get smaller and smaller until they form a cloud of junk that blocks the path of future space vehicles.

So what can be done to clean up the space around our planet? Marco Castronuovo, an Italian researcher, talks about sending a satellite into space that would get very close to some of the larger pieces of space junk. The satellite would connect a small rocket to the useless object. When the rocket explodes, it pushes the junk into a lower and slower orbit, nearer the earth. After a time, the junk burns up in the atmosphere.

Mr. Castronuovo has proposed (提议) using a number of small satellites with robotic arms. One arm would catch the space junk, and another arm would connect the rocket. He imagines that each satellite would jump from one large piece of junk to another. He thinks this method could destroy about ten large objects each year.

Scientists have been concerned about space junk for many years. Right now, the costs of the clean-up have been too great. Mr. Castronuovo says his system could be put in place for a much more reasonable amount of money.

1.Much of the space junk _____.

A．was thrown by the astronauts

B．is from broken spaceship

C．is made up of small pieces of things

D．returns to the earth piece by piece

2.Scientists are most worried that the space junk _____.

A．will stop the future space vehicles

B．will do harm to the atmosphere

C．will fall on the housetops

D．will burn up in space

3.What does Marco Castronuovo think of his system?

A．It can remove space junk completely.

B．It can save a large amount of money.

C．It can create a large amount of space.

D．It can develop robotic technology.

“Our aim is to take our art to the world and make people understand what it is to move,” said David Belle, the founder of parkour(跑酷).
Do you love running? It is a good exercise, yet many people find it boring. But what if making your morning jog a creative one? Like jumping from walls and over gaps, and ground rolls? Just like the James Bond in the movie Casino Royale? Bond jumps down from a roof to a windowsill and then runs several blocks over obstacles on the way. It is just because of Bond’s wonderful performances that the sport has become popular worldwide.
Yes, that’s parkour, an extreme street sport aimed at moving from one point to another as quickly as possible, getting over all the obstacles in the path using only the abilities of the human body. Parkour is considered an extreme sport. As its participants dash around a city, they may jump over fences, run up walls and even move from rooftop to rooftop.
Parkour can be just as exciting and charming as it sounds, but its participants see parkour much more than that.
Overcoming all the obstacles on the course and in life is part of the philosophy(理念) behind parkour. This is the same as life. You must determine your destination, go straight, jump over all the barriers as if in parkour and never fall back from them in your life, to reach the destination successfully. A parkour lover said, “I love parkour because its philosophy has become my life, my way to do everything.”
Another philosophy we’ve learnt from parkour is freedom. It can be done by anyone, at any time, anywhere in the world. It is a kind of expression of trust in yourself that you earn energy and confidence.
【小题1】Parkour has become popular throughout the world because of          .

When the big bills for mother's hospital care came, father was glad he had money in the bank to _____.

　　A. fall short of    B. fall through

　　C. fall back on     D. fall in with

The biggest safety threat（威胁）facing airlines today may not be a man with a gun ,but the man with portable（便携式）computer in business class .In the past 15 years ,pilots have reported about over 100 incidents that could have been caused by electro-magnetic interference(电磁干扰) .The source of this interference remain unclear ,but increasingly ,experts are pointing the blame at portable electronic devices（设备）such as portable computers ,radio and mobile telephones .
RTCA ,an organization which advises the aviation industry ,has suggested that all airlines ban, such devices from being used during “key” stages of flight ,particularly take-off and landing .Some experts have gone further ,calling for a total ban during all flights .Nowadays ,rules on using these devices are left up to airlines. And although some airlines ban passengers from using such equipment during take-off and landing ,most are not willing to exercise a total ban ,if many passengers want to work during flights .
The difficulty is understanding how electromagnetic fields might affect an aircraft’s computers .Experts know that portable devices give off radiation which affects those wave lengths which aircraft uses for communication .But because they have not been able to reproduce these effects in a laboratory ,they have no way of knowing whether the interference might be dangerous or not .
The fact that aircraft may be in trouble because of the interference raises the danger
that some people may use radio systems in order to damage navigation（导航）equipment .As worrying ,though ,is the passenger who can’t hear the instruction to turn off his radio because the music is too loud .
【小题1】.
.What is said about over 100 aircraft incidents in the past 15 years ?
A They may have taken place during take-off and landing .
B They have been caused by the damage to the radio systems .
C They were said to have resulted from electro-magnetic interference .
D They were caused by the passengers’ portable computers .
【小题2】.
. Few airlines want to refuse a total ban on their passengers because ____ .
A they have other effective safety measures to fall back on
B they don’t believe there is such a danger as radio interference
C the effect of electromagnetic interference is yet to be proved
D most passengers refuse to take a plane which bans the use of radio 
【小题3】.
. Why is it difficult to see the effects of electromagnetic fields on computers ?
A Experts lack proper equipment to such research .
B It is dangerous to carry out such research on an airplane .
C It remains a question what wave lengths are to be interfered with .
D Scientists are not able to produce the same effects in laboratory .
【小题4】.
It can be inferred from the passage that the author ___ .
A hasn’t formed his own opinion on this problem
B has fully understood the danger of electromagnetic interference
C regards it is as unreasonable to exercise a total ban during flight
D is in favor of banning passengers’ use of electronic devices