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    Disposing(处理) of waste has been a problem since humans started producing it. As more and more people choose to live close together in cities, the waste-disposal problem becomes increasingly difficult.

    During the eighteenth century, it was usual for several neighboring towns to get together to select a faraway spot as a dumpsite. Residents or trash haulers(垃圾托运者) would transport household rubbish, rotted wood, and old possessions to the site. Periodically(定期的) some of the trash was burned and the rest was buried. The unpleasant sights and smells caused no problem because nobody lived close by.

    Factories, mills, and other industrial sites also had waste to be disposed of. Those located on rivers often just dumped the unwanted remains into the water. Others built huge burners with chimneys to deal with the problem.

    Several facts make these choices unacceptable to modern society. The first problem is space. Dumps, which are now called landfills, are most needed in heavily populated areas. Such areas rarely have empty land suitable for this purpose. Property is either too expensive or too close to residential(住宅区的)neighborhoods. Long-distance trash hauling has been a common practice, but once farm areas are refusing to accept rubbish from elsewhere, cheap land within trucking distance of major city areas is almost nonexistent.

    Awareness of pollution dangers has resulted in more strict rules of waste disposal. Pollution of rivers, ground water, land and air is a price people can no longer pay to get rid of waste. The amount of waste, however, continues to grow.

    Recycling efforts have become commonplace, and many towns require their people to take part. Even the most efficient recycling programs, however, can hope to deal with only about 50 percent of a city's reusable waste.

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。选项中有两项为多余选项。

Don'tyou just love ice skating every winter? I am sure that since winter isapproaching, your skates are set to come out, just waiting to be used. Impressyour friends with a new trick on how to ice­skate backwards with the help ofthese trips.

Stand straight

 The first thing that you need to do is standstraight.____， if you feel that you are falling backwards. Don't worry；this happens to all.

 Confidence is what you need

Themost important step while learning how to skate backwards is having enoughconfidence in yourself and in what you are doing. How can you achieve this? Bypractice. One of the important ice skating tips and techniques is that if youfeel that you are losing your balance, then scissor (做剪式运动) your skates____.

 Maintain speed

 Try sculling with one skate while rolling in astraight line with the

 other____.Now bring the skate which you are using to scull, and then again,repeat the same process. Make sure that you put most of your weight on theskate which is moving straight and not the one with which you are sculling.Now, try the same thing using the other foot.

____

 Once you are confident that you can scull witheither foot, the next thing that you have to do is increase your speed. Trysome of your own tricks now. Scull with either foot or with both at the sametime.

 Scull and be aware

 While you keep one foot straight, keepsculling with the other. You can do that with both feet at the same time.____，but don't get so involved that you don't see where you are going. If you arenot watching your back, you might just bang into something or someone.

A．That is, keep pushing yourself backwards with an outwardstroke(滑动)

B．While going backwards, just get used to the feeling ofmoving backwards

C．Keep practicing this till you are confident about it

D．Increase your speed now

E．One must be brave enough to learn to ice­skate backwards

F．Concentrate on what you are doing

G．Just put your chin up and slightly bend your knees

72÷9=____