题目内容

龈下刮治放入器械时，工作端平面与牙根面之间成的角度是
A40°
B60°
C80°
D90°
E0°

查看答案

搜索结果不匹配？点我反馈

更多问题

According to Wesley Skogan, most of the explanations for reduced crime rates are incorrect.

根面平整的最终目的是()。
A去除根面残余牙石
B平整牙根面
C创造生物相容的环境
D用化学处理根面
E去除污染的牙骨质

Questions 5-8
Complete the following sentences using NO MORE THAN TWO WORDS from the text.
Unlike LCDs, electronic paper uses ______ to show information on screens.

Pollution is a "dirty" word. To pollute means to contaminate--topsoil or something by introducing impurities which make【C1】unfit or unclean to use. Pollution comes in many forms. We see it, smell it,【C2】it, drink it, and stumble through it. We literally lived in and breathe pollution, and【C3】surprisingly,it is beginning to【C4】our health,our happiness,and our civilization.
Once we thought of pollution【C5】meaning simply the smog—the choking, stinging, dirty【C6】that hovers over cities. But air pollution, while it is【C7】the most dangerous, is only one type of contamination among several【C8】attack the most basic life functions.
Through the uncontrolled use of insecticides, man has polluted the land,【C9】the wildlife. By【C10】sewage and chemicals into rivers and lakes, we have contaminated our【C11】water. We are polluting the oceans, too, kilting the fish and【C12】depriving ourselves【C13】an invaluable food supply.
Part of the problem is our exploding【C14】. More and more people are producing more wastes. But this problem is intensified by our "throw-away" technology. Each year Americans【C15】of 7 million autos, 20 million tons of waste paper, 25 million pounds of toothpaste tubes and 48 million cans. We throw away gum wrappers, newspapers, and paper plates. It is no longer wise to【C16】anything. Today almost everything is disposable.【C17】of repairing a toaster or a radio, it is easier and cheaper to buy another one and discard the old,even【C18】95 percent of its parts may still be functioning. Baby diapers,which used to be made of reusable cloth, are now paper throw-aways. Soon we will wear clothing made of【C19】:" Wear it once and throw it away" will be the slogan of the fashionable consciousness.
Where is this all to end？ Are we turning the world into a gigantic dump,or is there hope that we can solve the pollution problem？【C20】, solutions are in sight. A few of them are positively ingenious.
【C1】