Plant cloning has been an agricultural technique used by farmers and gardeners for centuries. Grafting (嫁接) is a common form of plant cloning. Many plants in nature actually clone themselves and reproduce asexually.
Cloned plants are much more predictable than normal plants, so their yield (产量) is more reliable. Cloned plants also reproduce faster, limiting the amount of time between planting and harvesting. It is also often cheaper to produce seeds through cloning than through traditional methods. Plants can essentially be optimized so that farmers or individual growers always have the best seeds available. With more yield at a faster rate, farms can produce more food for more people while decreasing overall costs.
Cloning can be used to wipe out diseases that previously killed off entire fields of crops. This would make plants immune (免疫的) to the kinds of diseases that farmers and gardeners around the world fear each year. Crop failures due to disease and virus could become a thing of the past. Also, plants that are near extinction can be brought back to life through cloning.
Through cloning scientists can develop “super” fruits and vegetables of superior nutritional quality. This could make for a healthier population overall. This is already being done through selective pollination (授粉), and genetic cloning could take it to the next level.
By plant cloning we have a population of identical plants and all these plants equally suffer from the same diseases, but in nature the weak would die and the strong would survive. While there are some dangers to consider with plant cloning, there are plenty of benefits that could prove vital to the propagation (繁衍) of the human species.
72. The underlined word “optimized” in Paragraph 2 can be replaced by “ ”.
A. enlarged B. produced
C. perfected D. examined
73. According to the text, cloned plants .
A. have lower yield than normal plants B. need little care from people
C. resist various kinds of diseases D. have a short growth cycle
74. What can we infer from the text?
A. The fruits produced by cloned plants taste much better.
B. There are more cloned plants than normal plants.
C. Plant cloning can disturb the laws of nature.
D. People should avoid eating cloned fruits.
75. What is the main purpose of the text?
A. To warn the negative effects of plant cloning.
B. To present different kinds of plant cloning.
C. To predict the future of plant cloning.
D. To inform us about the advantages of plant cloning.
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补充习题江苏系列答案科目：高中英语 来源：2013届云南省景洪市高二上学期期末考试英语试卷（解析版） 题型：完型填空
阅读短文，根据短文内容从A、B、C、D四个选项中选出最佳答案。
I had never been much interested in sports. I had tried playing tennis, swimming and running but found nothing I liked. But 10 years ago, I found the right kind of exercise--- 41 .
Why did I start walking? At the age of twenty, my doctor told me I had a serious illness and 42 not live longer. I was so 43 then. I spent all of my life worrying. The doctor suggested that I should 44 . I didn’t listen at first. 45 , after several months, I began to get the meaning of the doctor’s words. While I was walking, I began to 46 flowers. I would stop and enjoy their beauty. I 47 found that I had missed the most beautiful part of life--- flowers, falling leaves, snow-covered houses. I had been wasting time worrying about 48 .
Now I’m 35, and I don’t worry any more about 49 may happen, Worry only makes me miss the good things in 50 . I want to say hello to everything because I’m living a new life.
1. A．skating B．fishing C．riding D．walking
2. A．must B．need C．may D．should
3. A．happy B．worried C．excited D．bored
4. A．take more exercise B．watch more TV
C．play computer games less D．have enough sleep
5. A．If B．So C．Unless D．However
6. A．notice B．water C．pick D．plant
7. A．usually B．early C．quickly D．normally
8. A．pressure B．death C．study D．work
9. A．what B．when C．why D．where
10. A．season B．life C．book D．family
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科目：高中英语 来源：陕西省2010届高三适应性训练（英语） 题型：单词拼写
第一节：单词拼写（共10 小题；每小题1分，满分10分）
根据下列句子及所给汉语注释，在句子右边的横线上写出空缺处各单词的正确形式。（每空只写一词）
66．The _____________（设计） of the Amber Room was in the style still popular today．
67．A box of chocolates is a most________（受欢迎） gift for lovers on St Valentine’s Day
68．A fact is anything that can be ___________（证实）．
69．Ji Xianlin, an outstanding scholar, was ________（熟悉）with 12 foreign languages．
70．This is a photo taken by a _______________（职业）photographer．
71．__________（比较） with others, his idea sounds more reasonable．
72．Some _________（志愿者）offer help to “left behind children” in rural areas educationally．
73．On ______________（星期三），our teachers often have meetings．
74．This plant can be found in the __________（南部）parts of the country．
75．On hearing the funny story, all of us burst out ____________（大笑）．
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科目：高中英语 来源：陕西省2010届高三适应性训练（英语） 题型：阅读理解
第二部分：阅读理解（共20 小题。第一节共15 小题，每题2分；第二节共5 题，每题2分；共40 分）
阅读下列短文，从每题所给的四个选项 A．B．C．D中选出最佳选项。
A
Unnoticed and unappreciated for five decades，a large female turtle （龟）with a stained（彩色的），leathery（粗而硬的） shell is now a precious commodity（物品）in Changsha’s old zoo．She is fed on a special diet of raw meat．Her small pool has been covered with glass which can defend it from bullets．A special camera monitors her movements．A guard is posted at night．
The purpose is simple：the turtle must not die．
Earlier this year，scientists concluded that she was the planet’s last known female Yangtze giant soft shell turtle．She is about 80 years old and weighs almost 90 pounds．
As it happens，the planet also has only one known male．He lives at a zoo the city of Suzhou．He is 100 years old and weighs about 200 pounds．They are the last hope of saving a species believed to be the largest freshwater turtles in the world．
“It’s a very dangerous situation,” said Peter Pritchard, a famous turtle expert in the United States，who has helped try to save the species．、
For many Chinese people，the turtle is the symbol of health and long life，but the last two Yangtze giant soft-shell creatures show the threatened state of wildlife and biodiversity（生物多样性）in China．Pollution, hunting and over development are destroying natural habitats，and also endangering the plant and the animal population．
China contains some of the world’s richest treasures of biodiversity, yet the latest major survey of plants and animals shows a discouraging picture．Nearly 40 percent of all mammal species in China are now endangered, Scientists say．For plants，the situation is worse；70 percent of all nonflowering plant species and 86 percent of flowering species are considered threatened．
46．Why is the turtle in Changsha specially cared?
A．She has been unnoticed and unappreiated five decades．
B．She can be sold at a high price．
C．She is the planet’s last known female Yangtze giant soft-shell turtle．
D．She is old and heavy．
47．Which of the following statements is TRUE according to the text?
A．The turtle in Changsha is precious because it is the symbol of health and long life．
B．Peter Pritchard believes the female turtle is the largest freshwater turtle in the world．
C．The female turtle is in a dangerous situation where she may be killed．
D．The female turtle in Changsha and the male turtle in Suzhou are the last hope of saving the largest freshwater turtle species in the world．
48．According to the text ________in China．
A．there are the richest species of living things
B．wild plants and animals are becoming fewer
C．turtles are specially protected
D．the situation of plants is better than that of mammal species
49．The last paragraph proves the threatened state of wildlife and biodiversity in China by__________ ．
A．facts and numbers B．Peter Pritchard’S words
C．teaching theory D．telling a story
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科目：高中英语 来源：湖南省2010届高三5月月考英语试题 题型：单项填空
According to the recent regulation, it is required that any chemical plant that_______ along the river _______ to build a recycling center for the waste.
A. locate; has B. locates; have
C. is located; have D. is located; has
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科目：高中英语 来源：江苏省2010年高三下学期第四次模试考试英语试题 题型：阅读理解
The Grand Canyon (峡谷) in Arizona extends four hundred fifty kilometers. The canyons look as if they formed as the earth split apart. They were actually cut by rivers.
Looking at the Grand Canyon is like looking back in time. Forty million years ago, the Colorado River began cutting through the area. At the same time, the surrounding land was pushed up by forces deep within the Earth. Rain, snow, ice, wind, and plant roots rubbed away at the top of the new canyon. Below, the flowing river continued to uncover more and more levels of ancient rock. Their appearance changes endlessly -- with the light, the time of year, and the weather.
The Grand Canyon has several weather environments. The top is
often much different from the bottom. On some winter days, for example, you may
find cold winds and snow at the top. But at the bottom, you may find warm winds
and flowers.
The Grand Canyon is known as one of the seven wonders of the natural world. About five million people visit the canyon each year. Most visitors walk along paths part way down into the canyon. Some visitors ride mules to the bottom and back.
There are several other ways to visit the Grand Canyon. Hundreds of thousands of people see the canyon by air each year. They pay a helicopter or airplane pilot to fly them above and around the canyon.
About twenty thousand people a year see the Grand Canyon from the Colorado River itself. They ride boats over the rapid, rocky water. These trips last from one week to three weeks.
Visitors can see the Grand Canyon in still another way. A huge glass walkway, called the Skywalk, extends from the edge and is hanging above the bottom of the canyon.
Some people say the Skywalk is an engineering wonder. However, other people have criticized the Skywalk and future development. They say it harms a national treasure and reduces the enjoyment of nature in the Grand Canyon.
1. We can learn from the first paragraph ____________.
A. the Grand Canyon is the most beautiful place in America
B. the Grand Canyon is four hundred fifty kilometers long
C. the Grand Canyon used to be a dried river
D. the Grand Canyon used to be a deep opening in the earth
2. According to the passage, people can visit the Grand Canyon in ______ ways.
A. 3 B. 4 C. 5 D. 6
3. We can learn that the author of the passage hold a(n) ______ attitude towards the Skywalk.
A. positive B. negative C. objective D. critical
4. All the following are true about the Grand Canyon EXCEPT ____________.
A. The top of the Grand Canyon is always cold.
B. The Grand Canyon displays different colors in different times.
C. The Grand Canyon is as old as forty million years old.
D. Every year more people see the Grand Canyon by air than by boat.
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