If you walk through a park,you may enjoy the scents(气味）of flowers,water and soil.If you are especially lucky,you will get to smell fresh-cut grass.It's a beloved scent that transports many people back to their childhood.But there's a dark side to that smell.Indeed,we are in love with the scent of fear.
Plants have many different chemical defenses.That smell is one of them,as the grass responds to an attack,signaling(向......示意）to the surrounding grass that danger is coming.The fresh,"green”scent of a just-mowed lawn is the lawn trying to save itself,says a story at science website Real-Clear Science.
The smell is produced by a mix of chemicals called green leaf volatiles(GLVs,绿叶挥发物）.When the leafy plants are injured by animals eating them, people cutting them, or any other rough treatment-they give off GLVs into the air.These GLVs are a warning to neighbouring plants that their flowers might be removed,so they can move resources like sugar toward their roots and away from their flowers.This reduces a plant's potential losses and can help it grow back later.
The rush of GLVs does a few other things,too.One chemical helps to close the wound on the damaged plant.Others act as antibiotics(抗生素）and prevent bacterial infections.
Some GLVs may also react with animals that eat plants.Silke All-mann and Ian T.Baldwin, researchers from the University of Amsterdam,Netherlands,found that some caterpillars(毛虫）are changed by the GLV compounds(化合物）when they eat a tobacco plant.Tobacco makes the caterpillars more attractive to predators(捕食者）.For the tobacco plants,this is like having an older brother come to beat up your bully(欺凌者）.
Thankfully,nothing is coming to eat you when you mow the lawn.Instead,we human get treated to some great-smelling GLVs.One is a compound known as"cis-3-hexenal".This is the same chemical that gives strawberries their sweet scent.Similar compounds are also found in apples and olives.
＂Just about all fresh vegetables have some GLV scents to them,"Baldwin told Live Science,and fruits may release the compounds as they soften."Throughout evolutionary history,we've used that information to know when something is ripe,"Baldwin said.Now we can use it to know when grass is frightened.
1.What do we know about GLVs?
A.They are harmful to humans. B.They are unique to flowering plants.
C.They tend to stay in the air for a long time. D.They are released when plants get hurt.
2.How may plants react to the GLVs produced by neighbouring plants?
A.They grow more quickly. B.They produce more flowers.
C.They absorb more water. D.They transport resources to their roots.
3.In paragraph5,the underlined part"an older brother"refers to
A.a kind of antibiotic B.a predator. C.a caterpillar. D.a tobacco plant.
4.According to Baldwin,GLVs can
A.tell us whether fruits are ready to eat. B.protect plants from pests.
C.help fruits grow more quickly. D.help people choose delicious fruits.
你校将举办一次主题为“保护海洋”的图片展。请你根据以下要点为校宣传栏“英语天地”写一则通知：
1. 活动目的； 2.活动时间、地点、具体内容等。
注意：
1. 词数100左右；
2.可以适当增加细节，以使行文连贯。
参考词汇：展览exhibition
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假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的一下作文。文中共有10处语言错误，每句中最多有两处。每处错误涉及一个单词的增加、删除或修改。
增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。
删除：把多余的词作斜线（\）划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
注意：1. 每处错误及其修改均仅限一词；
2. 只允许修改10处，多者（从第11处起）不计分。
This afternoon after school, our English group get together with our English teacher. To start with, we sang a popular English song happy and then we practiced our speak English. The topic we were talking about was the different between Chinese festivals and Western ones. Most students compared the Spring Festival to Christmas and others chose the Mid-Autumn Festival or Thanksgiving Day as a match.
As we had been talked too many, all of us got quite thirsty. Seeing this, our teacher took some bottles of water from hers car and handed them out to us. What timely offer! Thank you, my dear teacher!
Nicolas Stacy-Alcantara was a 17-year-old high school student from Fresno. He said he______his friend near Salt Lake City last week and decided to go for a day-long hike alone with______to return in time for dinner.
Stacy-Alcantara said the weather had been______when he began his planned way from Millcreek Canyon(峡谷)to Park City. However, by late afternoon it became_____and snow began to fall. The weather______Stacy Alcantara to stop his journey. His cellphone had no______and his feet began to freeze(冻僵).
Being trapped in the snow, he______a cave to keep himself warm. He rubbed his hands against his______to keep the blood flowing.
“I knew my chest was more______than my feet,”he told reporters.
“I______if I lost those, I could still______, so I just tied the ends of my clothes together.
As the______fell, the teen______his friends were in the cave and had what he believed could be his______conversations with them. He also______letters to his family in case he didn't make it out alive.
He walked out of the______when the sun rose in the morning.______, he came across some skiers(滑雪者) who had a satellite phone. Later, he was______and he was about 6 miles from where he______his hike.
“I’m very______,” Stacy-Alcantara said. “I shouldn’t even be alive right now.”
1.A.lost B.visited C.cheated D.missed
2.A.plans B.excuses C.answers D.choices
3.A.windy B.wet C.cloudy D.warm
4.A.clear B.nice C.cold D.wild
5.A.forced B.helped C.reminded D.inspired
6.A.camera B.brand C.service D.map
7.A.decorated B.dug C.explored D.repaired
8.A.face B.head C.leg D.chest
9.A.important B.useful C.special D.comfortable
10.A.heard B.wondered C.asked D.knew
11.A.lie B.live C.study D.sleep
12.A.silence B.fear C.night D.sadness
13.A.guessed B.doubted C.explained D.imagined
14.A.simple B.final C.next D.normal
15.A.wrote B.sent C.read D.gave
16.A.cave B.room C.city D.valley
17.A.Suddenly B.Obviously C.Fortunately D.Interestingly
18.A.examined B.saved C.remembered D.warned
19.A.enjoyed B.followed C.avoided D.started
20.A.proud B.strong C.lucky D.clever
Concerts should be a fun and enjoyable occasion for everyone attending them, including the musicians. No matter what type of concert one is attending, he is still expected to follow the rules of concert etiquette(礼仪).1.
Classical music concerts are often events when concert etiquette is considered to be very important. One should generally arrive a few minutes before the show starts, so he can be in his seat at the beginning of the first musical performance. If he arrives late, it may be considered rude to walk in and take his seat in the middle of a musical performance.2.In this way, he will not influence other audiences while the music is being played.
3..Take jazz concerts for example. People are usually not criticized (批评) for making a small amount of noise, as long as it is not troubling other audiences. For example, they may talk quietly during a performance.
Rock and heavy metal concert etiquette is very relaxed4.However,audiences are still expected to show some good manners during a performance.Also, rock concerts are often very crowded, particularly in the areas surrounding the stage.
5.But one should still pay attention to his surroundings.Stepping on someone's foot repeatedly may cause a fight as well.
A.This will usually be announced before the concert begins.
B.Instead, he should wait for one song to end before taking his seat.
C.Rock concert goers, on the other hand, can usually get a little louder.
D.People are not usually discouraged from talking at these types of concerts
E.In large groups of people like this, it is not unusual to touch others at times.
F.Concert etiquette for other types of concerts is usually a little more relaxed.
G.And the concert etiquette can be different, depending on what type of concert it is.
More than 100 scientists from 25 countries have traveled to faraway places to collect wild crop seeds(种子) in an effort to help battle climate change.
The scientists, who have been compared to the heroes of the “Indiana Jones” movies, traveled on foot, four-wheeled vehicles(交通工具), boats, horses and even elephants to reach faraway areas. They faced extreme heat,dust, and danger from wild animals. At last, they collected 4, 644 seeds of 371 wild relatives of 28 world crops, many of which are said to be endangered.
The Crop Trust, an organization that works to save different kinds of crops, is directing the project. The group is working in partnership with Britain's Royal Botanic Gardens and Millennium Seed Bank. Additional financial support comes from Norway. The project is believed to be the largest organized international effort yet to collect and protect crops' wild relatives.Hannes Dempewolf is a scientist and the head at the Crop Trust. He said“What these seed collectors went through in the field resembles scenes from an Indiana Jones movie.”
Some crops are threatened because of destruction of forests, climate change and expanded cities. The newly-found wild seeds have developed so plants can grow in extreme temperatures, poor soils, and even in low rainfall areas.
A United Nations report says that food production is at risk because of a shortage of rain and other weather extremes connected to climate change. The U.N. Food and Agriculture Organization says that the number of plant species is quickly decreasing and people are depending on fewer species for food. Those wild seeds could be important in feeding a growing human population in some areas and offer a largely unused source of diversity(多样性) to crops.
1.What does the second paragraph show?
A.Collecting seeds is not an easy job.
B.The scientists’ story is made into a movie.
C.The wild seeds are in danger of extinction.
D.The scientists can choose from many vehicles.
2.What does the underlined word “resembles”in the third paragraph mean?
A.Depends on. B.Looks like.
C.Turns out. D.Refers to.
3.What is the advantage of the newly-found wild seeds?
A.They can increase green areas. B.They can provide more nutrients
C.They can survive bad conditions. D.They can improve existent crop seeds.
4.What is the meaning of the scientists collecting wild seeds?
A.Bringing more plant species to the world.
B.Helping farmers improve their farming skills.
C.Knowing about the worlds farming practices.
D.Helping battle climate change.
