在证券交易过程中，应当公正地对待证券交易的各方，以及公正地处理证券交易业务主要是说明

小王用实验室中一瓶失去标签的无色、无气味的浓溶液A进行探究实验．下列是他的实验操作步骤和现象的记录：

（1）取适量A于试管中，放入用砂纸打磨过的铝片，有大量无色无味气泡冒出．过一段时间后，将生成的气体导出用火去点，气体参燃烧．再用一个内壁附有澄清石灰水的烧杯罩在火焰上方，石灰水不变浑浊．

（2）取适量A于试管中，滴加一定量的稀硫酸，无明显变化．再滴加碳酸钠溶液，有大量无色无味气泡冒出．将生成的气体通入澄清石灰水，有白色沉淀生成．

（3）取适量A于试管中，滴加一定量的氯化铜溶液，有沉淀生成．

（4）取适量A于试管中，滴入几滴紫色石蕊试液，溶液变蓝色．

小王将实验操作步骤和现象的记录拿去请教化学老师．老师经过实验后告诉小王：“你所用的试剂标签正确，试剂没有变质，试管是干净的．你记录的现象也没有错，但有不完善的地方．溶液A中只有一种溶质且是初中化学中常见物质．A中的溶质、溶剂与铝反应只生成偏铝酸钠（NaAlO₂）和一种初中化学中接触过的单质．”小王经过推理得出了溶液A的成分．

请你推理后写出：

（1）A中溶质的化学式______；

（2）步骤②产生大量气泡的原因______；

（3）A与铝反应的化学方程式______；

（4）小王记录的实验现象不完善之处______．

I like that music, but the lyrics              good enough.    [ ]

A. aren't                      

B. are    

C. isn't .                      

D. is  

Comparisons were drawn between the development of television in the 20th century and the diffusion of printing in the 15th and 16th centuries. Yet much had happened between. As was discussed before, it was not until the 19th century that the newspaper became the dominant preelectronic mediam, following in the wake of the pamphlet and the book and in the company of the periodical. It was during the same time that the communications revolution speeded up, beginning with transport, the railway, and leading on through the telegraph, the telephone, radio, and motion pictures into the 20th - century world of the motor car and the air plane. Not everyone sees that processin perspective. It is important to do so.

It is generally recognized, however, that the introduction of the computer in the early 20th century, (48) by the invention of the integrated circuit daring the 1960s, radically changed the process, although its impact on the media was not immediately (49) . As time went by, computers became smaller and more powerful, and they became "personal" too, as well as (50) , with display becoming sharper and storage (51) increasing. They were thought of, like people, (52) generations, with the distance between generations much (53) .

It was within the computer age that the term "information society" began to be widely used to describe the (54) within which we now live. The communications revolution has (55) both work and leisure and how we think and feel both about place and time, but there have been (56) view about its economic, political, social and cultural implications. "Benefits" have been weighed (57) "harmful" outcomes. And generalizations have proved difficult.

57（）

A．above

B．upon

C．against

D．with

一个标准大气压等于多少（）mmhg

A.7.6

B.76

C.760

D.7600

墙杆是指脚手架的接点处与建筑结构之间的连接杆件。（）