E Trees should only be pruned when there is a good and clear reason for doing so and , he number of such reasons is small . Pruning involves the cutting away of overgrown and unwanted branches , and t 题目和参考答案——青夏教育精英家教网—

题目内容

Trees should only be pruned (修剪) when there is a good and clear reason for doing so and , he number of such reasons is small . Pruning involves the cutting away of overgrown and unwanted branches , and the inexperienced gardener can be encouraged by the thought that more damage results from doing it unnecessarily than from leaving the tree to grow in its own way .

First , pruning may be done to make sure that trees have desired shape or size . The object may be to get a tree of the right height , and at the same time to help the growth of small side branches , which will thicken its appearance or give it a special shape . Secondly , pruning may be done to make the tree healthier . You may cut out diseased or dead wood , or branches that are rubbing against each other and thus cause wounds . The health of a tree may be encouraged by removing branches that are blocking up the center and so preventing the free movement of air .

One result of pruning is that an open wound is left on the tree and this provides an easy entry for disease , but it is a wound that will heal (愈合) . Often there is a race between the healing and the disease as to whether the tree will live or die , so that there is a period when the tree is at risk . It should be the aim of every gardener to reduce that risk of death as far as possible . It is important to make the area , which has been pruned , smooth and clan , for healing will be slowed down by roughness . You should allow the cut surface to dry for a few hours and then paint it with one of the materials available from garden shops produced especially for this purpose . Pruning is usually done in winter , for then you can see the shape of the tree clearly without interference (妨碍) from the leaves and also it is very unlikely that the cuts you make will bleed . If this does happen , it is , of course , impossible to paint them properly .

71．Why should running be done ?

A．To make the tree grow taller . B．To improve the shape of the tree .

C．to get rid of the small ranches . D．To make the small branches thicker .

72．Trees become unhealthy if the gardener .

A．To help a wound to dry .

B．To cover a rough surface .

C．damages some of the small side branches

D．Allows too many branches to grow in the middle

73．Why is a special material painted on the tree ?

A．To help a wound to dry . B．to cover a rough surface .

C．To make a wound smooth . D．To prevent disease entering a wound .

74．A good gardener prunes a tree .

A．several times throughout the year B．as quickly as possible

C．occasionally when necessary D．regularly every winter

75．What was the author’s purpose when writing this passage ?

A．To discuss different methods of pruning .

B．To introduce some common knowledge of pruning .

C．To explain how trees develop disease .

D．To give practical instruction for pruning a tree .

【答案】

【解析】略

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【小题5】The People’s Republic of China was f_______ on October 1^st, 1949.
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第二节：（共5小题；每小韪分，满分10分）

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有多余选项。

51 The goal here is to limit carbon dioxide and other green house gases, which are closely associated to the big problem of global-warming．

Strategy 1: Bring your own cup to Starbucks

You’ll get a 10 cent discount, and it’s one less paper cup to end up in a landfill．While you’re there, pick up some free bags of spent coffee grounds to use as ‘‘green’’ fertilizer in your garden．

The payoff: 52

Strategy2: Turn off your computer

When in standby mode, your PC is still using energy． 53

The payoff: Turning off a monitor for 40 hours a week may only save $5 a month, but it reduces CO2 by 750 pounds

Strategy 3: Reuse plastic bags

Instead of throwing away 100 billion plastic bags a year, try and get a second, third, or tenth use out of them．Better yet, next time you shop, try a reusable bag．

The payoff: 54 The amount of oil it would take to make just 14 plastic bags would run your car for one mile．

Strategy4: Use recycled paper in the bathroom

Most of the toilet paper we use is made from trees found in forests previously untouched by humans．

The payoff: If every household replaced one roll of toilet paper with a recycled one, 424000 trees would still be standing．Look for eco paper towels too．

Strategy5: Buy energy-efficient appliances（电器）

Replace the old fridge with an Energy Star appliance and you’ll use 15 percent less energy． 55

The payoff: If we all used one Energy Star appliance at home, it would be like planting 1．7 million acres of new trees．

A．You can be proud of yourselves, even if you can only make one or two of these green changes.

B．Adding green to your garden is beautiful and earth-pleasing.

C．It might be a little expensive to buy, but you’ll save money on your electricity bills and help the environment．

D．In fact, 75percent of electricity used in your home comes from electronics that are turned off．

E．The store won’t create more waste when they throw away a cup．

F．The store won’t create more waste when they throw away a cup.

G．Just one tree will help make cleaner air and save the environment from 5000 pounds of hot carbon dioxide each year.

Plants can’t communicate by moving or making sounds, as most animals do. Instead, plants produce volatile compounds, chemicals that easily change from a liquid to a gas .A. flower’s sweet smell, for example, comes from volatile compounds that the plant produces to attract insects such as bugs and bees.

Plants can also detect volatile compounds produced by other plants. A. tree under attack by hungry insects, for instance, may give off volatile compounds that let other trees know about the attack, In response, the other trees may send off chemicals to keep the bugs away- or even chemicals that attract the bugs’ natural enemies.

Now scientists have created a quick way to understand what plants are saying: a chemical sensor（传感器） called an electronic nose. The “e-nose” can tell compounds that crop plants make when they’re attacked. Scientists say the e-nose could help quickly detest whether plants are being eaten by insects, But today the only way to detect such insects is to visually inspect individual plants. This is a challenging task for managers of greenhouses, enclosed gardens that can house thousands of plants.

The research team worked with an e-nose that recognizes volatile compounds. Inside the device, 13 sensors chemically react with volatile compounds. Based on these interactions, the e-nose gives off electronic signals that the scientists analyze using computer software.

To test the nose, the team presented it with healthy leaves from cucumber, pepper and tomato plants, all common greenhouse crops. Then the scientists collected samples of air around damaged leaves from each type of crop. These plants had been damaged by insects, or by scientists who made holes in the leaves with a hole punch （打孔器）.

The e-nose, it turns out, could identify healthy cucumber, pepper and tomato plants based on the volatile compounds they produce. It could also identify tomato leaves that had been damaged. But even more impressive, the device could tell which type of damage – by insects or with a hole punch – had been done to the tomato leaves.

With some fine tuning, a device like the e-nose could one day be used in greenhouses to quickly spot harmful bugs, the researchers say. A. device like this could also be used to identify fruits that are perfectly ripe and ready to pick and eat, says Natalia Dudareve, a biochemist at Purdue University in West Lafayette, Ind. who studies smells of flowers and plants. Hopefully, scientists believe, the device could bring large benefits to greenhouse managers in the near future.

1.We learn from the text that plants communicate with each other by______.

A. making some sounds B. waving their leaves

C. producing some chemicals D. sending out electronic signals

2.What did the scientists do to find out if the e-nose worked?

A. They presented it with all common crops..

B. They fixed 13 sensors inside the device.

C. They collected different damaged leaves.

D. They made tests on damaged and healthy leaves.

3.According to the writer, the most amazing thing about the e –nose is that it can ______.

A. pick out ripe fruits

B. spot the insects quickly

C. distinguish different damages to the leaves

D. recognize unhealthy tomato leaves

4.We can infer from the last paragraph that the e-nose_____.

A. is unable to tell the smell of flowers

B. is not yet used in greenhouses

C. is designed by scientists at Purdue

D. is helpful in killing harmful insects