When a leafy plant is under attack, it doesn’...

When a leafy plant is under attack, it doesn’t sit quietly. Back in 1983,two scientists,Jack Schultz and Ian Baldwin,reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be an alarm.What the plants pump through the air is a mixture of chemicals which are called VOCs for short.

Scientists have found that all kinds of plants give out VOCs when being attacked .It’s a plant’s way of crying out.But is anyone listening？Exactly.Because we can watch the neighbours react.

Some plants release smelly chemicals to keep insects away.But others do double duty .They pump out perfumes designed to attract different insects who are natural enemies to the attackers.Once they arrive,the tables are turned .The attacker who was lunching now becomes lunch.

In study after study,it appears that these chemical conversations help the neighbors .The damage is usually more serious on the first plant,but the neighbors ,relatively speaking ,stay safer because they heard the alarm and knew what to do.

Does this mean that plants talk to each other？ Scientists don’t know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in effect, was talking to itself. Perhaps the neighbors just happened to “overhear” the cry. So information was exchanged, but it wasn’t a true communication.

Charles Darwin, over 150 years ago, imagined a world far busier, noisier and more intimate(亲密的) than the world we can see and hear. Our senses are weak. The world is 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 .

1.Does a leafy plant sit quietly when it is under attack?

2.What does a plant do when it is under attack?

3.How can scientists know that there is someone listening to the crying?

4.What does the author mean by “the tables are turned” in paragraphs 3?

5.From the scientists' studies, can plants protect themselves against insects or really talk to each other?

6.What can be filled in the blank at end of the passage?

九年级英语回答问题困难题查看答案及解析

When a leafy plant is under attack, it doesn’t sit quietly. Back in 1983, two scientists, Jack Schultz and Ian Baldwin, reported that young maple trees getting bitten by insects send out a special smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be a warning. What the plants pump through the air is a mixture of chemicals known as volatile organic compounds（VOCs）.

Scientists have found that all kinds of plants give out VOCs when being attacked. It’s a plant’s way of crying out. But is anyone listening? Obviously. Because we can watch the neighbors’ react.

Some plants pump out smelly chemicals to keep insects away. But others do double duty. They pump out perfumes to attract different insects who are their natural enemies. Once the insects arrive, the tables are turned. The attacker who was lunching now becomes lunch.

In study after study, it appears that these chemical conversations help the neighbors. The damage is usually more serious on the first plant, but the neighbors stay safer because they heard the warning and knew what to do.

Does this mean that plants talk to each other? Scientists don’t know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in fact, was talking to itself. Perhaps the neighbors just happened to hear the cry by accident and so wrong information was exchanged.

Charles Darwin, over 150 years ago, imagined a world far busier, noisier and more intimate than the world we can see and hear, our senses are weak. There’s a whole lot going on.

1.What does a plant do when it is under attack?

A.It makes noises. B.It gets help from other plants.

C.It stands quietly. D.It sends out certain chemicals.

2.What does “the tables are turned” mean in Paragraph 3?

A.The attackers are attacked. B.The insects gather under the table.

C.The plants get ready to fight back. D.The perfumes attract natural enemies.

3.Scientists find from their studies that plants can__________.

A.talk to one another B.predict natural disasters

C.protect themselves against insects D.help their neighbors when necessary

4.What can we learn from the last paragraph?

A.The world is changing faster than ever. B.People have stronger senses than before.

C.The world is more colorful than it seems. D.People in Darwin’s time were full of imagination.

九年级英语阅读单选简单题查看答案及解析

Animals can move from place to place, but plants cannot. When an animal is under attack, it can run away or fight back. Plants certainly cannot run away, and they have no teeth or claws. But plants can still protect themselves in both physical and chemical ways.

Some plants have their own ways to keep animals away. For example, the leaves of the hollies(冬青树)　 have sharp spines (刺) that discourage grass-eating animals. Holly leaves on lower branches have more prickles than leaves on upper branches. This is because the lower leaves are easier for most animals to reach.

Some plants, such as the oak trees(橡树), have thick and hard leaves that are difficult for animals to eat. Some grasses may contain a sandy material，so eating such grasses wears down the animal's teeth

Many plants also have the chemical defense. Some plants produce chemicals that taste bitter or cause an unpleasant reaction. Some plants may protect themselves by increasing the production of these chemicals.　 When a worm(毛虫) bites a tobacco leaf, the leaf produces a chemical smell.

Many plants depend on both physical and chemical defense. A certain plant in China, for instance, has　 prickly (多刺的) leaves, and each prickle contains poisonous water(毒液).Only one experience with this kind of plant will teach an animal to stay away from it in the future.

1.What can a plant do when it is under attack?

A. It can protect itself

B. It can run away.

C. It can fight back.

D. It must die.

2.Why do the leaves of the hollies have sharp prickles according to the passage?

A. Because they are lower.

B. Because they are beautiful to watch.

C. Because they stop people from picking..

D. Because they make grass-eating animals stay away.

3.How does an oak tree protect itself?

A. It has leaves with a delicious material.

B. It has leaves with sharp prickles.

C. It has thick and hard leaves.

D. Its leaves taste bitter.

4.What does the underlined word“sandy” mean in Chinese?

A. 含盐的　　 B. 含沙的　　 C. 坏掉的　　 D. 腐烂的

5.Which of the following is TRUE according to the passage?

A. The hollies have thick and hard leaves.

B. The oak trees have leaves with poisonous water

C. A plant has only one kind of way to protect itself, physical one or chemical one.

D. A tobacco leaf produces a chemical smell when a worm bites it.

九年级英语阅读单选困难题查看答案及解析

– Is the baseball under the chair Jackie’s?

– It can’t be 　　　　 . He doesn’t like playing baseball at all.

A. him　　　　 B. his　　　　 C. he

九年级英语单项填空简单题查看答案及解析

–Oh! There is a snake in front of Jay.

--But it seems that he doesn’t ___the danger.

A. meet B. understand C. predict D. realize

九年级英语单项填空中等难度题查看答案及解析

Look! The tree is growing well. When______?

九年级英语单项填空中等难度题查看答案及解析

Look! The tree is growing well. When______?

A. was it planted                      B. did it plant

C. will it be planted                   D. is it planted[

九年级英语单项填空中等难度题查看答案及解析

- Look! The tree is growing well. When _____?

-Three years ago.

A. will it be planted　　 B. did it plant　　 C. was it planted　　 D. is it planted

九年级英语单选题中等难度题查看答案及解析

— Look! The tree is growing well. When 　　　　 ?

— Sorry, I don’t know, either.

A. was it planted　　　　　　　 B. has it been planted

C. is it planted　　　　　　　　 D. will it be planted

九年级英语单项填空困难题查看答案及解析

It is best not to talk loudly when you are in public. ________, keeping quiet in public is just one way to respect others.

A.In fact B.However C.Therefore

九年级英语单选题中等难度题查看答案及解析