问题 填空题

南宁至钦州段的高速铁路正在建设中。请回答下列问题:

(1)铁路建设中大量使用了以下材料:①石子;②钢筋水泥柱;③钢轨等,其中钢轨属于  A 

A.金属材料

B.合成材料

C.有机天然材料

D.无机非金属材料 (2)建设中,常用铝和氧化铁(Fe2O3)在高温条件下,反应生成熔融状态下的铁单质对钢轨中的缝隙进行焊接。反应的化学方程式为:Fe2O3+2Al 高温X+2Fe,则X的化学式为

 Al2O,该反应的基本类型是 置换反应

(3)钢轨长时间使用后会生锈。铁锈的主要成分是Fe2O3·xH2O;除铁锈常用的一种试剂是       。     

(4)请写出防止铁制品锈蚀的两种常用方法:① ;②      

答案

A    Al2O3  置换反应 稀盐酸       在表面涂油     涂上耐磨和耐腐蚀的镀层

 

判断题
完形填空

第二节(共5小题;每小题2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。选项中有两项为多余选项。

Americans are proud of their variety and individuality (个性), yet they love and respect few things more than a uniform, whether it is the uniform of a lift operator or the uniform of a five-star general( * * ).  71  .

Among the arguments for uniforms, one of the first is that in the eyes of most people they look more professional than civilian (百姓的) clothes.People expect higher quality from a man who wears a uniform.  72   .Faith in the skill of a garage mechanic is increased by a uniform.What easier way is there for a nurse, a policeman, a hairdresser, or a waiter to lose professional identity (职业身份) than to step out of uniform?

73  .They are often more comfortable and more lasting than civilian clothes.

Among the arguments against uniforms is their lack of variety and the loss of individuality experienced by people who must wear them.Though there are many types of uniforms, the wearer of any particular type is generally stuck with it, without change, until retirement.  74  .

75  .Though they are long-lasting, often their initial(最初的) expense is greater than the cost of civilian clothes.Some uniforms are also expensive to maintain, requiring professional dry cleaning rather than the home laundering possible with many types of civilian clothes.

A.Americans think highly of uniforms .

B.Why are uniforms so popular in the United States?

C.When people wear the same uniforms, they are likely to think, speak, and act similarly on the job at least.

D.Uniforms also have many practical good points E.Some practical problems with uniforms arise.

F.The television repairman who wears a uniform is likely to inspire more trust than one who appears in civilian clothes.

G.People's identity can be recognized more easily by their uniforms