[问题2] 如果以下3*3矩阵沿顺时针方向旋转90°后所形成的矩阵就是原来的矩阵：其

某化学课外小组的同学，在实验室实验时发现一瓶标签破损的无色溶液（如图），这瓶溶液是什么物质？在老师的指导下,同学们首先提出假设并进行了如下的探究活动。请在空白处完成相应内容。

（1）[提出假设]                               

（2）[实验及现象] ①在试管中取少量黑色粉末二氧化锰，向其中滴入该无色溶液，立即产生大量气泡，并放出大量的热。②将气体导出并用排水法收集一试管气体；③检验收集到的气体的方法及现象是                           该无色溶液是                    ，二氧化锰在此实验中起                         作用，反应的文字表达式为                               ，原假设成立。

981+982+983+984+985+986+987=984× （    ） = （    ） 

The common cold is the world's most widespread illness, which is a serious infection that man receives.

The most widespread mistake of all is that colds are caused by cold. They are not. They are caused by viruses passing on from person to person. You catch a cold by touching directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them forever. But they do not. And in separate Arctic (北极的)areas, explorers have reported being free from colds until touching again with infected people from the outside world by way of packages and mail dropped from airplanes.

During the First World War, soldiers who spent long periods in the trenches, cold and wet, seldom caught colds.

In the Second World War, prisoners at Auschwitz concentration camp, bare and starved, were astonished to find that they seldom had colds.

At the Common Cold Research Unit in England, volunteers took part in experiments in which they gave themselves to the discomforts of being cold and wet for a long time. After taking hot baths, they put on bathing suits, allowed themselves to be with cold water, and then stood about dripping wet in a room. Some wore wet socks all day while others exercised in the rain until close to exhaustion. Not one of the volunteers came down with a cold unless a cold virus was actually dropped in his nose.

If then, cold and wet have nothing to do with catching colds, why are they more frequent in winter? Despite the most hard research, no one has yet found out the answer. One explanation offered by scientists is that people tend to stay together indoors more in cold weather than at other times, and that makes it easier for cold viruses to be passed on.

No one has yet found a cure for the cold. There are drugs and pain-killers such as aspirin, but all that they do is to reduce the symptoms.

小题1:The writer thinks the cause of catching cold is due to_______.

A．touching anyone directly

B．touching anyone indirectly

C．cold weather

D．getting viruses from person to person小题2:Arctic explorers may catch colds when___.

A．they are working in the separate Arctic areas

B．they are writing reports in terribly cold weather

C．they are free from work in the isolated Arctic regions

D．they are coming into touch again with the outside world小题3:Volunteers taking part in the experiments in the Common Cold Research Unit___.

A．suffered a lot

B．never caught colds

C．often caught colds

D．became very strong小题4:The passage mainly discusses___.

A．the experiments on the common cold

B．the mistake about the common cold

C．the reason and the way people catch colds

D．the continued spread of common colds

简述薪酬管理的原则。

材料一：末作（工商业）文巧（华而不实）禁则民无所游食，民无所游食则必农，民事农则田垦，田垦则粟多，粟多则国富。国富者兵强，兵强者战胜，战胜者地广。……舍本而事末作，则田荒而国贫矣。

——《管子•治国》

材料二：“其余坊巷市井，买卖关扑，酒楼歌馆，直至四鼓方静，而五鼓朝马将动，其有趁卖早市者，复起开张。无论四时皆然。”

——（宋）耐得翁《都城纪胜》

材料三：海上（松江地区）官、民、军、灶，垦田几二百万亩；大半种棉，当不止百万亩。……壤地广袤，不过百里而遥，农亩之入，非能有加于他郡邑也。所繇共百万之赋，三百年而尚存视息者，全赖此一机一杼而已。非独松也，苏、杭、常、镇之币帛，嘉、湖之丝纩，皆恃此女红末业，以上供赋税，下给俯仰。若求诸田亩之收，则必不可办。

——明代徐光启《农政全书》卷-五《蚕桑广类•木棉》

概括材料一体现的经济主张及其理由。