Given a tree, you can find the only binary tree corresponding to it

’ life really say a lot more. Scientists are using tree tings to learn what's being happening on the sun's surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk taking up chemical elements from the air. By looking up the elements in the rings for a given year, scientists can tell what elements were in the air that year. Doctors Stevenson is analyzing one element—carbon-14 in ring from both living and dead trees. Some of the tings go back almost ten thousand years to the end of the Ice Age. When Stevenson followed the carben-14 trail back in time, he found carbon-4 levels change with the intensity of solar burning. You see, the sun has cycles. Sometimes it burns fiercely and other times it's relatively calm. During the sun's violent periods, it throws off charged particles in fast moving strings called solar winds. The particles interfere with the formation of carben-14 on earth. When there's more solar wind activity, less carbon-14 is produced. Ten thousand years of tree rings show that the carbon-14 level rises and falls about every 420 years. The scientists concluded that the solar wind activity must follow the same cycle.

What can the tree's rings tell us？

A．The age of the tree.

B．The changing activities of sun.

C．A lot more.

D．All the above.

听力原文： You can tell the age of a tree by counting its rings. But these records of tree's life really say a lot more. Scientists are using tree rings to learn what's been happening on the sun's surface for the last ten thousand years. Each ring represents a year of growth. As a tree grows, it adds a layer to its trunk taking up chemical elements from the air. By looking up the dements in the rings from the given year, scientists can tell what dements were in the air that year. Dr. Stevenson is analyzing one element—earbon14 in rings from both living and dead trees. Some of the rings go back almost ten thousand years to the end of the Ice Age. When Stevenson followed the carbon14 trail back in time, he found carbonn4 levels change with the intensity of solar burning. You see the sun has cycles. Sometimes it burns fiercely and other times it is relatively calm. During the sun's violent periods, it throws off charged particles in fast moving strings called solar winds. The particles interfere with the formation of carbon14 co. Earth. When there's mom solar rand activity, less carbon14 is produced. Ten thousand years of tree fines show that the carbon 14 level rises and falls about every 420 years. The scientists concluded that the solar wind activity must fellow the same cycle.

(26)

A．To examine the chemical elements in the Ice Age.

B．To look into the pattern of solar wind activity.

C．To analyze the composition of different trees.

D．To find out the origin of carbon14 on Earth.

听力原文： You can tell the age of a tree by counting its tings. But these records of a tree's life really say a lot more. Scientists are using tree tings to learn what's been happening on the sun's surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk, taking up chemical elements from the air. By looking at the elements in the rings from a given year, scientists can tell what elements were in the air that year.

Dr. Stevenson is analyzing one element, carbon—14, in rings from both living and dead trees. Some of the rings go back almost ten thousand years to the end of the Ice Age. When Stevenson followed the carbon--14 trail back in time, he found carbon—14 levels change with the intensity of solar burning. You see the sun has cycles. Sometimes it bums fiercely. At other times it's relatively calm. During the sun's violent periods, it throws off charged particles in fast moving streams, called solar winds. The particles interfere with the formation of carbon—14 on earth. When there is more solar wind activity, less carbon—14 is produced. Ten thousand years of tree rings show the carbon—14 level rises and falls about every four hundred and twenty years. The scientists concluded that solar wind activity must follow the same cycle.

(30)

A．To find out the origin of carbon- 14 on Earth.

B．To analyze the composition of different trees.

C．To look into the pattern of solar wind activity.

D．To examine the chemical elements in the Ice Age.

ow. Change the form if necessary. olive tree; poplar; pine; Chinese fir; oak; teak; eucalyptus; Pinus patula __________ which can be used to make furniture or boatbuilding, is a tropical hardwood species placed in the family Lamiaceae.

Q1 Search Trees How many nodes are in the complete search tree for the given state space graph？ The start state is S. You may find it helpful to draw out the search tree on a piece of paper.

听力原文： I am one of the many city people who are always saying that given the choice we would prefer to live in the country away from the dirt and noise of a large city. I have managed to convince myself that if it weren't for my job I would immediately head out for the open spaces and go back to nature in some sleepy village buried in the country. But how realistic is the dream？

Cities can be frightening places. The majority of the population live in massive tower blocks, noisy, dirty and impersonal. The sense of belonging to a community tends to disappear when you live fifteen floors up. All you can see from your window is sky, or other blocks of flats. Children become aggressive and nervous confined at home all day, with nowhere to play; their mothers feel isolated from the rest of the world. Strangely enough, whereas in the past the inhabitants of one street all knew each other, nowadays people on the same floor in a tower block don't even say hello to each other.

Country life, on the other hand, binds the inhabitants of small villages together. People have the advantage of knowing that there is always someone to turn to when they need help. But country life has disadvantages too. While it is tree that you may be among friends in a village, it is also true that you are cut off from the exciting and important events that take place in Cities. There's little possibility of going to a new show or the latest movie. Shopping becomes a major problem, and for anything slightly out of the ordinary you have to go on an expedition to the nearest large town. The city-dweller who leaves for the country is often oppressed by a sense of unbearable stillness and quiet.

(30)

A．He used to live in the country.

B．He used to work in the city.

C．He works in the city.

D．He lives in the country.

ad-A MOMENT'S INATTENTION CAUSES ACCIDENTS. This self-defeating warning has now been removed but its message is still very much to the point. Almost anything can cause an accident. Apart from momentary inattention, it might be a minor miscalculation. Although human error plays its part, it is by no means the only cause of accidents. There must be some causes other than simple human error. Road construction also plays its part. It is on those roads where there arc subtle visual traps. Wherever there is a "black spot", it means that something is seriously wrong with the road.

If you have been involved in an accident and have been stopped, you must give your name, address, and registration number to anyone who has a good reason for requesting it; this means anyone affected by the accidents. If somebody is injured, the driver must produce his insurance certificate on request. If these formalities are complied with it is not necessary to wait for the arrival of the police. It is, however, often wise to do so. The police are expert at drawing plans, taking measurements and photographs and gathering other evidence. In your absence the police could be given a biased story against you; and you yourself might want to point out certain features of the accident to the police.

A MOMENT'S INATTENTION CAUSES ACCIDENTS is a self-defeating warning because______.

A．it is not tree

B．it will distract the driver's attention

C．it is too difficult to understand

D．it is too long to be read while driving a car

To decide whether you can successfully transplant a tree yourself, you should ______.

A．select your location carefully

B．measure the ball of earth around the tree roots

C．measure the diameter of the tree trunk

D．cut off as many taproots as you can reach

Put the following words in a hierarchical order(you can use a tree diagram if need be)and try to define at least two of them:(北师大2003研) crocodile, mammal, reptile, rabbit, primate, animal

A.a ship, a plane or a car

B.a tree

C.a horse

D.a house