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Broken rubber bands and flat tires requiring replacement could soon be a thing of the past. French researchers have developed a new kind of rubber that can repair itself when broken.The new rubber is made from widely available materials including vegetable oil and a common industrial chemical.All the materials are considered safe to the environment and can be easily reused. The best part is that the new rubber can be repaired and used again and again without losing its strength or ability or stretch.When cut, the rubber can be made new again, simply by pressing the two broken ends back together. The product can be repaired at room temperature, around twenty degrees Centigrade;other self-healing materials require higher temperatures for repair. Traditionally, rubber substances are made from huge molecules(分子)connected by strong chemical links, or bonds.The new rubber is made of smaller molecules.The molecules are linked together using hydrogen bonds.When connected in this way, the molecules act like one long molecule, forming what is called supramolecular networks(超分子网).When the rubber is cut, the molecules attempt to connect with whatever molecule is near them.When pressed together, the molecules are able to repair themselves at the molecular level, making the repaired rubber like new. However, time is an important element in the process.If the broken ends are not brought together quickly, a repair is not possible.This is because molecules will form bonds with molecules on their own side.The inventors say the surfaces of the rubber can be repaired within a week of being separated. The rubber is the creation of scientists at the Industrial Physics and Chemistry Higher Education Institution in Paris.The organization is part of France’s National Center for Scientific Research.The new material is described in greater detail in the research publication Nature. 小题1:According to the introduction, which of the following is NOT the advantage of the new rubber? A.It can be made as easily as common rubber. B.It is environmentally-friendly. C.It can repair itself at room temperature. D.It is made of smaller molecules. 小题2:What does the 5th paragraph mainly tell us? A.Why the new rubber is unique. B.Why the new rubber can repair itself. C.The new rubber is made from huge molecules. D.The new rubber is different from the common rubber. 小题3:If we want to know more about the technology of this kind of new rubber, where can we get the information? A.In the researchers’ diary. B.In a guide book. C.In a research magazine. D.In a newspaper.
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A.
450kN.m
B.
498kNkN.m
C.
530kN.m
D.
568kNkN.m
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A.
正确
B.
错误
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A.
口腔内气味
B.
口腔的温度
C.
口腔粘膜的颜色
D.
口腔的湿度
E.
舌苔及牙齿
【判断题】桥梁桩基一般连接系梁或承台,系梁或承台底部为桩顶。()
A.
正确
B.
错误
【判断题】交互分配法特点是辅助生产费用通过一次分配即可完成,减轻分配工作量。( )
A.
正确
B.
错误
【多选题】承台联系梁设置正确的是( )。
A.
单桩承台,应在两个互相垂直的方向上设置联系梁
B.
两桩承台,应在其短向设置联系梁
C.
两桩承台,应在其长向设置联系梁
D.
有抗震要求的柱下独立承台,宜在两个主轴方向设置联系梁
E.
联系梁底面宜与承台底面位于同一标高
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A.
用料和工具
B.
体积和空间
C.
色彩和线条
D.
形象和造型
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【单选题】患者,女性,32岁,一个月前因外伤一上前牙冠折,现要求烤瓷修复。口腔检查: 牙冠2/3缺损,根管口有充填物存在,无松动,叩(-),余未见异常。 修复前要检查的主要内容除了()
A.
根尖片
B.
咬合情况
C.
儿有无松动
D.
其它牙的缺损情况
E.
拍曲面断层片
【单选题】分析下列程序: public class class4{ private string _sData=""; public string sData{set{_sData=value;}} }在main函数中,在成功创建该类的对象obj后,下列哪个语句是合法的?
A.
obj.sDate= "It is funny!";
B.
Console.WriteLine(obj.sData);
C.
obj._sData = 100;
D.
obj.set(obj.sData);
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