Your cell phone holds secrets about you. Besides the names and numbers that you’ve programmed into it, traces of your DNA remain on it, according to a new study.
DNA is genetic material that appears in every cell. Like your fingerprint, your DNA is unique to you --- unless you have an identical twin. Scientists today usually analyze DNA in blood, saliva(唾液), or hair left behind at the scene of a crime. The results often help detectives identify criminals and their victims.
Meghan J. McFadden, a biologist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the device. This made her wonder whether traces of DNA remained on cell phones --- even when no blood was involved. To find out, she and a colleague collected flip-style(翻盖式) phones from 10 volunteers. They collected invisible traces of the users from two parts of the phone: the outside, where the user holds it, and the speaker, which is placed at the user’s ear.
The scientists scrubbed(meaning “cleaned”) the phones using a liquid mixture made mostly of alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones back for another week. Then the researchers collected the phones and repeated collecting traces on each phone once more. They discovered DNA that belonged to the phone’s owner on each of the phones.
Surprisingly, DNA showed up even in swabs that were taken immediately after the phones were cleaned. That suggests that washing won’t remove all traces of evidence from a criminal’s cell phone. So cell phones can now be added to the list of clues that can help a crime-scene investigation. McFadden decided to find out whether people leave their DNA on their cell phones when she ____ .
| A．got her cell phone lost by chance |
| B．found a cell phone with blood on it |
| C．heard about a crime involving a cell phone |
| D．did research on cell phones |
The scientists allowed the volunteers to keep their cell phones for a week in order to____.
| A．let them leave their traces on their phones |
| B．avoid keeping their cell phones too long |
| C．give them a chance to get rid of their secrets |
| D．find out who is responsible for the crime |
The last paragraph mainly tells us that cell phones ____ .
| A．do harm to people | B．should be often cleaned |
| C．disclose people’s secrets | D．help deal with crimes |
Which of the following is NOT mentioned in the passage?
| A．The reason for collecting the phones from volunteers. |
| B．The technique of collecting DNA on the phones. |
| C．The method of removing traces of DNA on the phones. |
| D．The purpose of washing the cell phones. |
People like different kinds of vacations. Some go camping. They swim, fish, cook over a fire and sleep outside. Others like to stay at a hotel in an exciting city. They go shopping all day and go dancing all night. Or maybe they go sightseeing to places such as Disneyland, the Tai Mahal or the Louvre.
Some people are bored with sightseeing trips. They don’t want to be “tourists”. They want to have an adventure— a surprising and exciting trip. They want to learn something and maybe help people too. How can they do this? Some travel companies and environmental groups are planning special adventures. Sometimes these trips are difficult and full of the world. Some volunteers spend two weeks and study the environment. Others work with animals. Others learn about people of the past.
Would you like an adventure in the Far North? A team of volunteers is leaving from Murmansk, Russia. The leader of this trip is a professor from Alaska. He’s worried about chemicals from factories. He and the volunteers will study this pollution in the environment. If you like exercise and cold weather, this is a good trip for you. Volunteers need ski sixteen kilometers every day. -
Do you enjoy ocean animals? You can spend two to four weeks in Hawaii. There, you can teach language to dolphins. Dolphins can follow orders such as “Bring me the large ball”. They also understand opposites. How much more can they understand? It will be exciting to learn about these intelligent animals. Another study trip goes to Washington State and follows orcas. We call orcas “Killer Whale”, but they’ re really dolphins—the largest kind of dolphin.. These beautiful animals travel together in family groups. They move through the ocean with their mothers, grandmothers and great-grandmothers. Ocean pollution is chasing their lives. Earthwatch is studying how this happens.
Are you interested in history? Then Greece is the place for your adventure. Thirty-five hundred years ago a volcano exploded there, on Santorini. This explosion was more terrible than Krakatoa or Mount Saint Helens. But today we know a lot about the way of life of the people from that time. There are houses, kitchens, and paintings as interesting as those in Pompei. Today teams of volunteers are learning more about people from the past.
Do you want a very different vacation? Do you want to travel far, work hard and learn a lot? Then an Earthwatch vacation is for you.The Tai Mabal may be _________.
| A．a shopping center | B．a hotel |
| C．a dancing ball | D．a place of interest |
From the passage, on an adventure trip, people ______________.
| A．may not spend much time on sightseeing |
| B．won’ t meet some difficulties or hardships |
| C．can’t enjoy themselves - |
| D．can’t learn something |
If you want to learn something about people of the past, you can ___________
| A．join the team to Hawaii | B．join the team to the Far North |
| C．join the team to Washington | D．join the team to Greece |
The word “intelligent” in paragraph 4 means __________________.
| A．exciting | B．beautiful | C．large | D．clever |
Which of the following is false ?
| A．Some people find sightseeing trips boring. |
| B．Earth watch is planning all these special adventures |
| C．The number orcas is decreasing. |
| D．3 volcano explosions in all broke out 3, 500 years ago in Greece. |
What do you do if you're stranded (处于困境的) on a lonely island? Surely you need to find a way to get in touch with the outside world. Your best chance of doing this is to draw the attention of a passing plane.
Body signals (信号)
Pilots from different countries understand body signals if they have the correct training. When you wave your arms up and down in a straight line, it means "yes". When you point downwards and swing your arm from side to side, it means "no". If you want the pilot to know that it's safe to land, push your hands out in front of you and bend (弯曲) your knees. If you want to say that it's not safe to land, put your arms in the air and move them to one side.
Smoke signals
The smoke from a fire can be seen from far away, so it's a good way to draw attention. If the weather is dry, it isn't hard to start a fire. Remember, however, that fires can be very dangerous if they get out of control. Never light a fire unless you're sure that it can't spread. If the ground is dark, light smoke can be seen more easily. Green grass and leaves produce light smoke.
Ground-to-air signals
It's a good idea to build some signals, too. Use large pieces of wood to make the symbols (标记). If you can't find any wood, use earth. Some useful symbols are:
F: I need food and water."
II: I need medicine."
I: I am badly hurt."
X: I am unable to move from here."
Pilots' replies
If the pilot lowers the plane's wings from side to side, this means "message received and understood". (At night, the pilot flashes the plane's green lights.) If the pilots flies the plane in a clockwise circle, this means "message received but not understood". (At night, the pilot flashes the plane's red lights.)Which picture means "it's not safe to land"?
What can we learn from the passage?
| A．Swinging your arm from side to side means "yes". |
| B．If the ground is dark, light smoke can't be seen. |
| C．If you need some medicine, make a symbol "II". |
| D．The pilots make replies with a blue light at night. |
What is the passage mainly about?
| A．The explanation of building signals on an island. |
| B．The importance of making signals on an island. |
| C．Ways of sending out signals on a lonely island. |
| D．Ways of receiving signals from a lonely island. |
Dereck Joubert and his wife, Beverly, have made many films about wild animals in Africa. Their films and photographs are very popular and one of the photographs has been on the front cover of a National Geographic magazine.
A working day for Dereck and Beverly started very early—at 4:30 in the morning! That’s when they get up and start filming. And it’s a long day—they often work until 8:30 in the evening. In the winter it’s very cold and in the summer it can be 40C. Dereck always does the filming—Beverly never does that, and she doesn’t write. But Dereck never takes photographs or records the sound. They work very well as a team, and they both believe we should shoot animals with cameras—not with guns!
When they have finished filming and taking photographs for the day, they have dinner and Dereck usually writes while Beverly looks at her photographs. At night, they usually sleep in a small tent, but they sometimes sleep in the Land Cruiser—when they’re very close to wild animals, it’s sometimes safer to sleep in the car!
Dereck and Beverly have also traveled around the world and given talks about their work. Dereck says that the animals are not just something to look at—they play an important role. Beverly thinks the wild animals can teach us a lot about ourselves.Dereck and Beverly start working_________.
| A．at 4:30 in the morning |
| B．at 4:30 in the afternoon |
| C．at 8:30 in the morning |
| D．at 8:30 in the evening |
Dereck and Beverly usually sleep_________ at night.
| A．in a car | B．in a tent |
| C．in a house | D．in a hotel |
Beverly thinks the wild animals __________.
| A．are something to look at | B．are very popular |
| C．play an unimportant role | D．can teach us a lot |
Scientists believe that one of our most important means of knowing what is going on around us is the sense of sound. We are warned of danger by sounds. Sounds serve to please us in music. Sound has a waste product, too, in the form of noise. Noise has been called unwanted sound. Noise is growing and it may get much worse before it gets any better.
In order to know how noise affects people and animals, scientists have been studying for several years. They are surprised by what they have learned. Peace and quiet are becoming harder to find. Noise pollution is a threat that should be looked at carefully.
Sounds is measured in units called decibels (分贝). At a level of 140 decibels people feel pain in their ears.
Trucks , buses , motorcycles, airplanes, boats, factories---all these things make noise. They trouble not only our ears, but minds and bodies as well.
There is a saying that it is so noisy that you can’t hear yourself think. Doctors who study noise believe that we must sometimes hear ourselves think. If we don’t, we may have headaches, other aches and pains, or even worse mental problems.
Noise adds more tension (紧张) to a society that has already faced enough stress.The sense of sound _________.
| A．makes us feel excited |
| B．helps us hear more clearly |
| C．is something harmful to us |
| D．helps to know what is happening around us |
When sound is turned into noise, ______________.
| A．people grow worse and worse |
| B．it makes us forget all the past |
| C．people don’t know what to do with everyday life |
| D．it will be a kind of pollution to people |
Why does the passage say peace and quiet are becoming harder to find?
| A．Because the world is making more and more noise. |
| B．Because wars and battles happen here and there in the world. |
| C．Because all the sounds are becoming over 140 decibels. |
| D．Because some machines can make noise. |
Doctors say we can hear ourselves think __________.
| A．if we don’t like to hear noise |
| B．if we have no aches or pains in our bodies |
| C．if there isn’t too much noise |
| D．if we can’t be careful of noise |
Once in a busy street, a middle-aged businessman found his wallet missing. There was a lot of money in it. So he made a promise, "If someone finds my wallet and returns it to me, I'll give half the money to him."
The wallet was found by a dustman in a dustbin. He sent it back to the loser. But the businessman changed his mind.
"There was still a diamond ring in my wallet," said the loser, "I won't give half the money in my wallet to you until you return it to me!"
"I've never seen a diamond ring in the wallet," said the dustman.
They began to quarrel. The businessman refused to do what he had said. The dustman became angry and took him before a judge.
After the judge heard what had happened to them, he said to the businessman, "I'm sure you are an honest man. It's true that you have lost a wallet in which there was a diamond ring. But it's also clear that there is only a lot of money in this wallet. I don't think it's yours. Wait for some time. Perhaps someone will be able to return your wallet to you!"
Then the judge turned to the dustman and said, "Take the wallet home. If the loser doesn't go to get it back in three days, it will belong to you!"The wallet the businessman lost ________.
| A．was found in a shop |
| B．was sent to the judge |
| C．was found in a dustbin |
| D．was never to be found |
The businessman was eager to get back the wallet because _________.
| A．there was the address of an important judge in it |
| B．he put in it a diamond ring he had just bought |
| C．there was a lot of money in it |
| D．it was a very expensive one |
Having heard what had happened, the judge _________ .
| A．took the side of the businessman |
| B．did not know what to do |
| C．took pity on the loser |
| D．made a wise decision |