Plants can’t communicate by moving or making sounds, as most animals do. Instead, plants Produce volatile compounds, chemicals that easily change from a liquid to a gas. A flower’s sweet smell, for example, comes from volatile compounds that the plant produces to attract insects such as Bugs and bees.
Plants can also detect volatile compounds produced by other plants. A tree under attack by Hungry insets, for instance, may give off volatile compounds that let other trees know about the Attack. In response, the other trees may send off chemicals to keep the bugs away ——or even Chemicals that attract the bugs’ natural enemies.
Now scientists have created a quick way to understand what plants are saying: a chemical Sensor(传感器)called an electronic nose. The “e-nose” can tell compounds that crop plants make When they’re attacked Scientists say the e-nose could help quickly detect whether plants are being Eaten by insects. But today the only way to detect such insects is to visually inspect individual Plants. This is a challenging task for managers of greenhouses, enclosed gardens than can house Thousands of plants.
The research team worked with an e-nose than recognizes volatile compounds. Inside the device, 13 sensors chemically react with volatile compounds Based on these interactions, the e-nose gives off electronic signals that the scientists analyze using computer software.
To test the nose, the team presented it with healthy leaves from cucumber, pepper and tomato plants, all common greenhouse crops. Then scientists collected samples of air around damaged leaves from each type of crop, These plants had been damaged by insects, or by scientists who made holes in the leaves with a hole punch(打孔器). The e-nose, it turns out, could identify healthy cucumber, pepper and tomato plants based on The volatile compounds they produce, It could also identify tomato leaves that had been damaged. But even more impressive, the device could tell which type of damage ---- by insects or with a hole Punch ---- had been done to the tomato leaves.
With some fine-tuning, a device like the e-nose could one day be used in greenhouses to quickly spot harmful bugs, the researchers say. A device like this could also be used to identify fruits that are perfectly ripe and ready to pick and eat, says Natalia Dudareva, a biochemist at Purdue University in West Lafayette, Ind. who studies smells of flowers and plants. Hopefully, scientists believe, the device could bring large benefits to greenhouse managers in the near future.We learn from the text that plants communicate with each other by____.
A.making some sounds | B.waving their leaves |
C.producing some chemicals | D.sending out electronic signals |
What did the scientists do to find out if the e-nose worked?
A.They presented it with all common crops. |
B.They fixed 13 sensors inside the device. |
C.They collected different damaged leaves. |
D.They made tests on damaged and healthy leaves. |
According to the writer, the most amazing thing about the e-nose is that it can___.
A.pick out ripe fruits |
B.spot the insects quickly |
C.distinguish different damages to the leaves |
D.recognize unhealthy tomato leaves |
We can infer from the last paragraph that the e-nose_____.
A.is unable to tell the smell of flowers |
B.is not yet used in greenhouses |
C.is designed by scientists at Purdue |
D.is helpful in killing harmful insects |
People all need friends because nobody wants to be lonely and a friend can help you in good and bad times.You’ve made friends since childhood,but you still don’t know who your true friends are.Here are some signs to tell you if your friend is a true friend:
Always honest
Honesty is important to keep a relationship alive.A true friend always tells you the truth.It may be hard sometimes but lying can destroy a friendship.It is important that your friend speaks honestly and never makes up stories.
_________________
There are always periods in your life when you have problems or difficulties. A true friend will always have time to listen to your problems and give advice.It may not be able to offer a solution to your problems but the fact that your friend made time to listen is a sign he/she cares for you. Your friend is not a true friend if he/she can never make time for you when you are in trouble.You also need to be reasonable and accept that your friend also has other things to do so he/she can’t always listen immediately to your problems.
Always respectful (尊敬的)
A true friend will always respect your opinion no matter whether he/she agrees or not.Your true friend may disagree but never insists that he/she is correct.
Always understanding
It is possible that some problems will arise between you and your friend.A true friend will always be forgiving (体谅的) and understanding,even if it isn’t his/her fault.We are all different people and we all make mistakes.A true friend is always forgiving and understanding because he/she doesn’t want to take the risk of losing his/her best friend.What’s the best title for the third paragraph?
A.Always there for you | B.Keep your secrets |
C.Always happy for you | D.Remember your important days |
According to the passage,a true friend will always.
A.follow your advice |
B.offer a solution to your problems |
C.listen immediately to your problems |
D.respect your opinion even if he/she disagrees with it |
Which of the following is NOT mentioned in the passage?
A.Never tell lies to friends. |
B.Making time for friends. |
C.Sharing fun with friends. |
D.Paying attention to a friend’s opinions. |
A true friend will always forgive and understand you because.
A.he/she wants to help you |
B.he/she doesn’t want to lose you |
C.he/she wants you to feel confident |
D.he/she doesn’t care about your mistakes |
The world itself is becoming much smaller by using modern traffic and modern communication means. Life today is much easier than it was hundreds of years ago, but it has brought new problems. One of the biggest problems is pollution. To pollute means to make things dirty. Pollution comes in many ways. We see it, smell it, drink it and even hear it.
Man has been polluting the earth. The more people, the more pollution. Many years ago, the problem was not so serious because there were not so many people. When the land was used up or the river was dirty in one place, man moved to another place. But this is no longer true.
Man is now slowly polluting the whole world.
Air pollution is still the most serious. It’s bad for all living things in the world, but it is not the only one kind of pollution. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us angry more easily.
Many countries are making rules to fight pollution. They stop people from burning coal in houses and factories in the city, and from putting dirty smoke into the air. Pollution by SO2 is now the most dangerous kind of air pollution. It is caused by heavy traffic. We are sure that if there are fewer people driving, there will be less air pollution.
The earth is our home. We must take care of it. That means keeping the land, water and air clean. And we must take care of the rise in pollution at the same time._______, our world is becoming much smaller.
A.Because of the rise in pollution |
B.Thanks to science development |
C.Because the earth is being polluted day and night |
D.Because the earth is blown away by the wind every year |
Hundreds of years ago, life was __________ it is today.
A.much easier than | B.as easy as |
C.much harder than | D.as hard as |
Pollution comes in many ways. We can even hear it. Here “it” means _______.
A.rubbish(垃圾) | B.noise pollution |
C.air pollution | D.water pollution |
Air pollution is the most serious kind of pollution because _______.
A.it makes much noise |
B.it makes us angry more easily |
C.it makes our rivers and lakes dirty |
D.it’s bad for all living things in the world |
Which of the following is NOT true?
A.Many countries are making rules to fight pollution. |
B.The pollution of the earth grows as fast as the world population does. |
C.The problem of pollution is not so serious because there are not so many people living on the earth. |
D.If people could go to work by bus or bike instead of car or motorbike, it would be helpful in fighting against the problem of SO2. |
Some time ago, a friend of mine punished his three-year-old daughter for wasting a roll of gold wrapping paper. Money was tight(困窘的), and he became infuriated when the child tried to decorate a box to put under the Christmas tree. Nevertheless, the little girl brought the gift to her father the next morning and said, “This is for you, Daddy.” He was embarrassed by his earlier over-reaction, but his anger flared again when he found that the box was empty.
He shouted at her loudly, “Don’t you know that when you give someone a present, there’s supposed to be something inside of it?”
The little girl looked up at him with tears in her eyes and said, “Oh, Daddy, it’s not empty. I blew kisses in the box. I filled it with my love. All for you, Daddy.”
The father was crushed. He put his arms around his little girl, and he begged her for forgiveness(原谅). My friend told me that he kept that gold box by his bed for years. Whenever he was discouraged, he would take out an imaginary(假想的)kiss and remember the love of the child who had put it there.
In a very real sense, each of us as parents has been given a gold container filled with unconditional love and kisses from our children. There is no more precious possession(财产)anyone could hold.Why did the father punish his daughter?
A.Because the girl had torn his favourite paper. |
B.Because the girl was wasting a roll of gold wrapping paper. |
C.Because the girl took the box under the Christmas tree away. |
D.Because the father was in bad temper(脾气). |
Why did the father become angry again when he opened his present?
A.Because the present is not suitable for him. |
B.Because his daughter didn’t know that when she gives someone a present, there’s supposed to be something inside of it. |
C.Because he hated receiving present. |
D.Because he found that the present box was empty. |
What kind of present did the little girl give her father?
A.The little girl had put her kisses in the box as a present. |
B.The little girl had kissed the box as a present. |
C.The little girl had filled the box with gold wrapping paper. |
D.The little girl had filled the box with air. |
How did the father feel after he listened to his daughter’s explanation?
A.Happy. | B.Sorry. |
C.Crazy. | D.Impatient. |
What’s the meaning of the last sentence—“There is no more precious possession(财产)anyone could hold.”?
A.The possession is too heavy to hold. |
B.There’s no more precious thing for us to hold. |
C.It’s not necessary to hold the possession. |
D.The present contained with children’s love and kisses is the most precious thing. |
Mr Smith made many tests (作试验) with different animals and the monkey was the cleverest of all the animals.
One day Mr Smith put a monkey in a room. He also put some small boxes in it. In one of the boxes there was some food. "How long will it take the monkey to find the food? " Mr Smith said to himself. " Let me wait and see. " He left the room and waited outside. Three minutes later, he put his eye to the keyhole (钥匙眼). What did he see? He saw the eye of the monkey. The monkey was on the other side of the door and looked at Mr Smith through the keyhole.Mr Smith made tests with __________.
A.different animals | B.the monkey only |
C.all the monkeys | D.all of the cleverest animals |
There was some food in _______ of the small boxes.
A.some | B.none | C.one | D.each |
Mr Smith put a monkey and some boxes in a room because he wanted to know___________.
A.how much food monkey could find |
B.how many boxes the monkey could carry |
C.how long it would take the monkey to put its eye to the keyhole |
D.how long it would take the monkey to find the food |
What was the monkey doing when Mr Smith was putting his eye to the keyhole?
A.The monkey was eating food. |
B.The monkey was looking for food. |
C.The monkey was eating on the other side of the door. |
D.The monkey was looking at Mr Smith through the keyhole. |
Mr Smith is a ________.
A.teacher | B.scientist (科学家) |
C.doctor | D.farm worker |
Doctor Mason has held a clinic for ten years. He is an expert doctor. He usually gets up at 7:00 a.m. and commutes to work by subway. It’s always very crowded with people and he tries to keep his distance from them. In the winter he notices the stress on the faces of the commuters and knows that some of these people will come to him for advice. He always solves their problems and returns to the comfort of his home a satisfied man.
Martin is a gifted artist. He knows that he has an unusual occupation(职业), but he actually treats it as a disciplined career. He gets up at the same time every day and works for nine hours with a break for lunch. His new project uses metal but his designs use pencil and paper. In nine months’ time, his work will be on display outside the local library, and he will be very proud of it.What kind of transportation does Doctor Mason usually take?
A.bus | B.underground |
C.boat | D.bicycle |
What does Doctor Mason often do when he’s in a subway which is crowded with people?
A.He tries to take the next one. |
B.He gives up and tries to take a taxi. |
C.He tries to keep his distance from the tube. |
D.He tries to keep his distance from the people. |
What’s the possible meaning of the word “gifted” in the passage?
A.intelligent | B.stupid |
C.common | D.strange |
What does he use in his design?
A. metalB. metal and pencil
C. pencil and paper D. Both A and C.Which of the statements is NOT true?
A.When Doctor Mason notice the stress on people’s face in winter, he knows that some of these people will come to him for advice. |
B.Doctor Mason often feel satisfied after he helps people with their problems. |
C.Martin is very strict with his work. |
D.Martin has to work for nine hours without a break everyday. |