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Many men tried to fly like birds．They made wings 1 themselves，usually of feathers，and tried to fly 2 moving their wings as a bird 3 None of them 4 ．A bird has a very 5 body but very strong wing 6 ．A man，on the contrary，has a 7 body and not very strong arm muscles．A man will 8 fly like a bird．His muscles are not strong enough．He can only fly properly 9 with an engine．
There is kind of plane which doesn't have an engine．It 10 a glider（滑翔机）．It is very light and can carry 11 one or two people．It is pulled into the air rather like flying a kite，usually from a 12 place if there is a good 13 ，it can rise into the air and sometimes cover long 14 but usually it soon glides gently back to 15 ．
Some men did not find sitting in a glider exciting enough．They wanted to glide by 16 wings，like the“bird men”of old 17 ．But the wings of he modem“ bird men” were 18 ．They were 19 ．They were not made 20 feathers．
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Redwood trees are the tallest plants on the earth，reaching heights of up to 100 meters．They are also known for their longevity，typically 500 to 1000 years，but sometimes more than 2000 years．A hundred million years ago，in the age of dinosaurs，redwoods were common in the forests of a much more moist and tropical North America．As the climate became drier and colder，they declined to a narrow strip along the Pacific coast of Northern Califomia．
The trunk of redwood trees is very strong and usually forms a single straight column．It is covered with a soft bark．This bark can be pretty thick，well over two feet in the more mature trees．It gives the older trees a certain kind of protection from insects，but the main benefit is that it keeps the center of the tree harmless from moderate forest fires because of its thickness．This fire resistant quality explains why the giant redwood grows to live that long．While most other types of trees are destroyed by forest fires，the giant redwood actually prospers because of them．
Moderate fires will clear the ground of competing plant life，and the rising heat dries and opens the ripe fruit of the redwood，releasing many thousands of seeds onto the ground below．
??? New trees are often produced from shoots，little baby trees，which form at the base of the trunk．These shoots grow slowly，fed by the root system of the “mother’’ tree．When the main tree dies，the shoots are then free to grow as full trees，forming a “fairy ring” of trees around the original tree．These trees，in turn，may give rise to more shoots，and the cycle continues．
1.Why were redwood trees easier to find in the forests of North America millions of years ago?
A．The trees were taller and stronger．
B．The soil was softer for seeds to develop．
C．The climate there was warmer and wetter．
D．The temperature was lower along the Pacific coast．
2.Which of the following is a function of the tree bark as mentioned in the passage?
A．It allows redwood trees to bear seeds．
B．It prevents redwood trees from attack by insects．
C．It helps redwood trees absorb water in the air．
D．It makes redwood trees more beautiful and appealing．
3.Why do redwood trees grow to live that long according to the passage?
A．They have heavy and straight tree trunks．
B．They are properly watered and catered to．
C．They are more resistant to fire damage than other trees．
D．They produce many young trees to maintain their life cycle．
4.How does a “fairy ring’’ form according to the passage?
A．By killing an old tree．????????????? ????????????? ????????????? ????????????? B．By connecting root systems．
C．By inserting holes into old trees．????????????? ????????????? D．By surrounding a mature tree．
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