计算：6423=______．

到目前为止还没有国家的大洲是（　　）

A．非洲

B．大洋洲

C．南极洲

D．南美洲

A、B、C、D、E、F六种物质的转化关系如图所示（反应条件和部分产物未标出）．

（1）若A为短周期金属单质，D为短周期非金属单质（一种黑色固体），且所含元素的原子序数A是D的2倍，原子的最外层电子数D是A的2倍，化合物F的浓溶液与单质A、D在一定条件下反应都有红棕色气体生成，则A在周期表中的位置为：______，B的电子式为：______，F的浓溶液与D在加热条件下反应的化学方程式为：______．

（2）若A是常见变价金属的单质，D、F是气态单质，且反应①②均在水溶液中进行．则反应②的离子方程式是______．

（3）若A、D、F都是短周期非金属元素单质，且 A、D所含元素同主族，A、F所含元素同周期，B是制作光导纤维的基本原料，则B是______，C是______，F是______．（填化学式）

Life gets noisier every day and very few people can be free from noise of some sort or another. It doesn't matter where you live--in the middle of a modern city, or a faraway village--the chances are that you' ll be disturbed by jet planes, radios, oil - powered engines, etc. We seem to be getting used to noise, too. Some people feel quite lonely without background music while they' re working.

Scientific tests have shown that total silence can be a very frightening experience for a human being. However, some people enjoy listening to pop music which is very loud, and this can do harm to their eardrums(耳鼓). The noise level in some discos is far above the usual safety level for heavy industrial areas.

One recent report about noise and concentration(专心) suggested that although a lot of people say that any noise disturbs their concentration, what really influences their ability to concentrate is a change in the level of noise. It goes on to say that a background noise which doesn't change too much(music, for example) may even help people to concentrate.

小题1:According to this passage, the noise pollution         .

A．has become the worst in the countryside

B．has become better in big cities

C．has spread from cities to villages

D．has been controlled in modern cities小题2:Some people have their hearing harmed        .

A．while listening to pop music

B．in complete silence

C．when speaking loudly

D．while watching TV小题3:Scientists have discovered that what prevents people from concentrating on something is        .

A．all kinds of noise

B．changes in the level of noise

C．background noise

D．popular music

《高层民用建筑设计防火规范》规定：建筑高度不超过100m的一类高层建筑的下列部位应设置火灾自动报警系统（）

A.商业楼

B.商住楼的营业厅

C.商住楼的住宅户内

D.展览楼的展览厅

下列民事法律关系中，可以以行为作为客体的是( )。

A．物权

B．债权

C．人格权

D．继承权