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问题 单项选择题

关于起重机以下说法中，不正确的是（）。

A.吊钩起重机的额定起重量不包括吊钩和动滑轮组的自重

B.起重机的利用等级反映了起重机在吊重方面的满载程度

C.轮胎起重机、全路面起重机和履带起重机均可吊重行驶

D.桥式起重机主要由桥架、大车运行机构、小车运行机构、起升机构和电气设备组成

答案

参考答案：B

解析：

起重机的利用等级反映起重机工作的繁忙程度，起重机的载荷状态反映起重机在吊重方面的满载程度。

单项选择题 A1/A2型题

关于缺隙保持器适应证描述错误的是（）

A.乳牙早失，恒牙胚牙根形成大于1／2

B.间隙有缩小的趋势

C.多数乳磨牙早失，影响患儿咀嚼功能

D.牙冠上覆盖有较厚的骨组织

E.乳牙早失，恒牙胚牙根尚未发育
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问答题

People today all over the world are beginning to hear and learn more and more about the problem of pollution. (46) Pollution is caused by either the release by man of completely new and often artificial substances into the environment, or by releasing greatly increased amounts of a natural substance, such as oil from oil tankers into the sea.
(47)The whole industrial process which makes many of the goods and machines we need and use in our daily lives, is bound to create a number of waste products which upset the environmental balance, or the ecological balance as it is also known. (48) Many of these waste products can be prevented or disposed of sensibly, but clearly while more and more new goods are produced and made complex, there will be new, dangerous wastes to be disposed of, for example, the waste products from nuclear power stations.
(49)Whatever its underlying reasons, there is no doubt that much of the pollution caused could be controlled if only companies, individuals and governments would make more efforts. In the home there is an obvious need to control litter and waste. Food comes wrapped up three or four times in packages that all have to be disposed of; drinks are increasingly sold in bottles or tins which cannot be reused. This not only causes a litter problem, but also is a great waste of resources, in terms of glass, metals and paper. Advertising helped this process by persuading many of us not only to buy things we neither want nor need, but also to throw away much of what we do buy. (50)Pollution and waste combine to be a problem every one can help to solve by cutting out unnecessary buying, excess consumption and careless disposal of the products we use in our daily lives.
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