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Birds in cities are damaging their health by trying to sing above the noise of urban life．

New research shows that male birds are trying to compete against traffic and city sounds．They are now singing louder and at higher frequencies，which could harm their vocal cords．Some birds are choosing to sing at night instead of dudng the day．This makes them more open to attack and also creates stress and exhanstion．

“The difference between urban and rural birdsong is becoming so big that the two groups could now be unable to communicate．This could lead to inbreeding and a weak gene pool．”said Dr Sue Anne Zollinger of the University of St Andrews．

According to Zollingar,a bird group with a small geae pool might adapt less quickly to new diseases and could be wiped out．

A study of the dawn chorus found that birds in Berlin sang up to 14 decibels(分贝)louder than those in the forest．The birds sang loudest on weekday momings．

“By trying to sing over the sound of the city,birds are rising vocal injury,”said Zollinger．“All this puts the sarne strain on a bird’s vocal cords as when  ahuman need to shout to be heard—except the birds are doing it all day,every day,”she said．

“Singing under such pressure means birds have less control over the sound they produce． Their songs may lose quality and become more rough—sounding．”said Zollinger．This could make them appear less attractive to female birds．

Mark Constantine，author of The Sound Approach to Birding，said：“Birdsong is important for our quality of life and has been proved to reduce our blood pressure．When we live in the centre of large，urban areas，we get stressed and it's extremely good to have birdsong around us．The impact on humans of birdsong is massive．It harms us，as well as the birds，if their songs become louder and simpler

53．Some birds in cities now choose to sing at night time because_______．

A．they want to attract more birds of opposite sex

B．they are more likely to be discovered by their family

C．they can’t adapt to the loud noises during the daytime

D．they have to frighten their enemy away

54．According to the passage，urban and rural birds might not be able to_______．

A．recognize each other

B  communicate with each other

C  live with each other

D．compete against each other

55．It requires greatest efforts for birds in cities to sing o_______．

A．Monday nights            B．Wednesday afternoons

C．Saturday Evenings         D．Friday momings

56．According to Dr Sue Anne Zollinger,birds singing louder might eventually lead to_______．

A．the harm done to man’s health

B  the dying out of a species

C．the serious damage to the bird’s vocal cords

D．the decrease ofthe birth rate ofa bird group

Trees are useful to man in three important ways: they give him wood and other useful things, they give him cool places, and they help to stop drought and flood.

Unluckily, in many parts of the world, man has not found that the third of these points is the most important. Man wants to make money from trees, so he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And also, he is usually too careless to plant and look after new trees. So the forests slowly disappear.

This does not only mean that man will have fewer trees. The results are even worse: for where there are trees, their roots break up soil-make the rain in-and also bind the soil, thus stopping it from being washed away easily; but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When all the top-soil is gone, nothing is left but useless desert.

1.The most important points of trees to man is ________.

A. they help him to make money               B. they give him cool

C. they give him wood and other things       D. they help him to stop drought and floods

2.In many places forests slowly disappear because ________ .

A. many trees have been cut down by man

B. new trees are not well looked after

C. man has not paid enough attention to planting trees

D. all the above

3.Land becomes desert after all trees are cut down because ________ .

A. roots of trees break up the soil   

B. there are too many rainfalls

C. strong winds bring a lot of sand

D. there are no longer trees to keep the rain and protect the top-soil.

4.Which title best fits the passage?

A. Trees and Man                                      B. The Function of Tree Wood

C. How do People do with Trees?                  D. The Usage of Tree Roots

Trees are useful to man in three important ways: they give him wood and other useful things, they give him cool places, and they help to stop drought and flood.
Unluckily, in many parts of the world, man has not found that the third of these points is the most important. Man wants to make money from trees, so he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And also, he is usually too careless to plant and look after new trees. So the forests slowly disappear.
This does not only mean that man will have fewer trees. The results are even worse: for where there are trees, their roots break up soil-make the rain in-and also bind the soil, thus stopping it from being washed away easily; but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When all the top-soil is gone, nothing is left but useless desert.
【小题1】The most important points of trees to man is ________.

Trees are useful to man in three important ways: They provide him with wood and other products; they provide him shade;. and they help to prevent droughts（早灾）and floods.
Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important．In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear.
This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soil allowing the rain to sink in and also bind（固定）the soil, thus preventing it from being washed away easily；but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When the top-soil is gone, nothing remains but worthless desert.
Two thousand years ago，a rich and powerful country cut down its trees to build warships, with which to gain itself an empire(帝国）．It set up the empire, but, without its trees, its soil became poor and grew weak. When the empire fell to pieces, the home country found itself faced by floods and starvation（饥荒）．
【小题1】The most important service of trees to man is that___________．

Trees are useful to man in three important ways: They provide him with wood and other products; they provide him shade;. and they help to prevent droughts（早灾）and floods.

    Unfortunately, in many parts of the world, man has not realized that the third of these services is the most important．In his eagerness to make money from trees, he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And besides, he is usually too careless to plant and look after new trees. So the forests slowly disappear.

    This does not only mean that man will have fewer trees. The results are even more serious: for where there are trees, their roots break up soil allowing the rain to sink in and also bind（固定）the soil, thus preventing it from being washed away easily；but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-soil. When the top-soil is gone, nothing remains but worthless desert.

    Two thousand years ago，a rich and powerful country cut down its trees to build warships, with which to gain itself an empire(帝国）．It set up the empire, but, without its trees, its soil became poor and grew weak. When the empire fell to pieces, the home country found itself faced by floods and starvation（饥荒）．

1.The most important service of trees to man is that___________．

   A. they give them wood and other products      B. they give them shade

   C. they help him prevent droughts and floods    D. they help him made money

2.In many parts of the world, forests slowly disappear because___________．

   A. many trees have been cut down by man    B. man has not paid enough attention to planting trees

   C. new trees are not looked after properly     D. all the above

3.Land becomes desert after all trees are cut down because____________．

   A. roots of trees break up the soil              B. there are too many rainfalls

   C. there are no larger trees to keep rain and protect the top-soil   D. strong winds bring a lot of sand

4.The country mentioned in the passage suffered from floods and starvation  because________.

   A. it set up an empire             B. the empire fell to pieces

   C. it built too many warships       D. it lost its trees

5.Which title best fits the passage?

   A. Trees and Man               B. How Trees Prevent Droughts and Floods

   C. How an Empire Fell          D. A Story about Trees.