Plants have family values,too,it seems,with new research sug?gesting they can recognize close relatives in order to work together.

An ability to tell family from strangers is well known in animals,allowing them to cooperate and share resources,but plants may pos?sess similar social skills,scientists believe.

Susan Dudley and Amanda File of McMaster University in Ontario? Canada,report they have demonstrated for the first time that plants can recognize their kin.

This suggests that plants,though lacking recognition and memory,are capable of complex social interactions.

"Plants have this kind of hidden but complicated social life," Dudley said.

The study found plants from the same species of beachdwelling wild flower grew aggressively alongside unrelated neighbours but were less competitive when they shared soil with their families.

Sea rocket,a North American species,showed stronger and healthier root growth when planted in pots with strangers than when raised with relatives from the same ma?ternal (母系的) family,the study found.

This is an example of kin selection,a behaviour common in animals in which closely related individuals take a group approach to succeeding in their environment,the researchers said.

Kin selection also applies to competition,because if family members compete less with each other,the group will do better overall. "Everywhere you look,plants are growing right up next to other plants," Dudley said. "Usually it's a case of each plant for itself. But sometimes those plants are related,and there are bene?fits to not wasting resources on being competitive,and there is not really a cost to not being competitive as long as your neighbour is also not being competitive."

Learning and memory appear to be important for kin recognition in animals,but this isn't an option for plants,she noted.

Some researchers speculate (猜测) that plants communicate through their roots,identifying themselves using tiny chemical signatures specific to each plant's family.

5. What's the main idea of the passage?

   A. Studies find plants can recognize and communicate with relatives.

   B. Kin selection is important for plants.

   C. Animals can recognize and memorize their relatives.

   D. Competition asks plants to recognize their relatives.

6. Which of the following is NOT right about animals' social skills?

   A. Animals can recognize and memorize their relatives.

   B. Animals' social skills are to cooperate and share resources.

   C. Animals' social skills can recognize close relatives to work together.

   D. Animals' social skills are no use at all.

7. Plants' kin selection is to         .

   A. grow well

   B. compete with other kinds of plants

   C. strengthen the relationship among siblings

   D. find which one is the best

8. From the passage,we learn that         .

   A. sea rocket is a South American species

   B. sea rocket grows aggressively alongside unrelated neighbours

   C. sea rocket grows aggressively alongside its siblings

   D. sea rocket is a kind of bush without flowers

A In the atmosphere,carbon dioxide allows the sun's rays to enter but prevents the heat from escaping. According to a weather expert's prediction,the atmosphere will be warmer in the year 2050 than it is today,if man continues to burn fuels at the present rate. If this war?ming up took place,the ice caps in the poles would begin to melt,thus raising sea level several metres and severely flooding coastal cities. Also,the increase in at?mospheric temperature would lead to great changes in the climate of the northern hemisphere.

In the past,concern about manmade warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctica,which may be affected by only a few degrees of warming,in other words,by warming on the scale that will possibly take place in the next fifty years from the burning of fuels. Satellite pictures show that large areas of Antarctic ice are already disappea?ring. The evidence suggests that warming has taken place. This fits the theory that carbon dioxide warms the earth.

However,most of the fuel is burnt in the northern part of the earth,where temperatures seem to be falling.  Scientists conclude,therefore,that up to now natural influences on the weather have exceeded those caused by man. The question is：Which natural cause has most effect on the weather?

One possibility is the behaviour of the sun. Astronomers at one research sta?tion have studied the hot spots and cold spots,that is,the relatively less hot spots,on the sun. This seems to have a greater effect on the distribution of the earth's at?mospheric pressure,and consequently on wind circulation (循环) .The sun is also variable (可变的) over a long term. Its heat output (输出) goes up and down in cycles. The latest trend being downward is on the way. But that is only an imagination.

1. The carbon dioxide in the atmosphere would       .

   A. prevent the sun's rays from reaching the earth's surface

   B. mean warming up in the Arctic

   C. account for great changes in the climate

   D. raise the temperature of the earth's surface

2. The article is written to explain       ,

   A. the greenhouse effect

   B. the solar effects on the earth

   C. the solar weather

   D. the causes affecting weather

3. Although the fuel is greater in the northern part,temperatures there seem to be falling. This is       .

   A. mainly because the carbon dioxide is rising

   B. possibly because the ice caps in the poles are melting

   C. due to the effect of the earth's climate

   D. partly due to the activity of the sun

4. What does the underlined word "exceeded" in Paragraph 3 mean?

   A. To be the same as. B. To be slower than.

   C. To be better than. D. To be bigger than.

There is no doubt 1.        the earth is becoming warmer but there is fierce debate over whether it is human activity that has caused this global warming or whether it is just a natural phenomenon.

Many scientists like Dr Janice Foster believe that people have caused the increase in the earth's temperature 2.        burning of fossil fuels like coal,natural gas and oil to produce energy 3.        byproducts are called "greenhouse" gases,the most important one 4.        carbon dioxide. These gases trap heat from the sun and therefore warm the earth,without which the earth 5.        (be) about thirtythree degrees Celsius cooler than it is. But increased amount of carbon dioxide means that 6.        (much) heat energy is trapped in the atmosphere,7.        (cause) the global temperature to go 8.       .

On 9.       other hand,scientists like George Hambley believe that any warming will be mild with few bad 10.        (environment) consequences and more carbon dioxide is actually a positive thing.

result in,even though,glance at,come about,on the whole

1. Tom        the newspaper and handed it to me.

2. You are hurting me very greatly. I still may not forgive you,        you apologize.

3. Our sport team,          ，was good. Only one player didn't do so well.

4. The singer's flight was put off due to bad weather,         the show being cancelled (取消) .

5. It's already 10 o'clock. I wonder how it          that she was two hours late on such a short trip.

5. ―Excuse me. Can you spare me a few minutes? 

—What's         ？

4. ―Why are you making so much noise? 

―I just can't help            ,

3. More heat energy will be trapped in the atmosphere,causing the global temper?ature to go          .

2.          average,there are 200 visitors to the exhibition every day.

1. The problem of global warming is serious. As             consequence,the sea levels have risen a little.

10. Lydia doesn't feel like        (study) abroad. Her parents are old.