有一透明溶液,可能含有较大量的Mg2+、Fe3+、Al3+、Cu2+、Na+、H

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问题:

有一透明溶液,可能含有较大量的Mg2+、Fe3+、Al3+、Cu2+、Na+、H+、SO42-、CO32-中的一种或几种,取此溶液做下列实验:①取少量溶液加入用盐酸酸化的BaCl2溶液,有白色沉淀生成;

②取少量溶液加入过氧化钠粉末,溶液中有白色沉淀产生并逸出无色无味的气体,加入Na2O2的物质的量与析出沉淀的物质的量如图所示.试推断:

(1)溶液中一定含有的离子是______.

(2)溶液中肯定不含有的离子是______.

(3)可能含有的离子是______.

考点:离子的检验
题型:填空题

结构化分析方法(SA)是一种预先严格定义需求的方法,强调分析对象的 (51) 。其指导思想是 (52)

A.程序流

B.指令流

C.数据流

D.控制流

题型:填空题

根据实验回答下列问题:

(1)DNA的粗提取实验中可以选用鸡血做实验材料,是否可用羊、牛、马的血做实验材料?

(2)在加冷酒精提取丝状物过程中,要用玻璃棒沿一个方向缓慢搅拌溶液,为什么?

(3)从上清液中析出的丝状物是否能代表DNA分子?

题型:填空题

More and more Italians are leaving their country because they can not get a job. One in every three Italians say they are willing to go abroad, sometimes even to other continents to get work. Currently, about 300,000 young Italians may be living abroad.

Although emigration has always been a choice for Italians, especially for those who left the country at the beginning of the twentieth century, more young Italians think leaving their home country is the only way to escape economic difficulty. These young Italians, however, are not poor farmers or laborers but bright university graduates and other talented young people.

Many of them want to go to richer places, like northern Europe, but they are also prepared to go elsewhere. Most of them describe a feeling of unhappiness and frustration. They are not sure which direction their country is heading and feel no longer proud of being Italians.

Many leave because they think that getting a good job is possible in other countries where all doors are open to you if you are young and dynamic. However, in Italy everything is boring and old-fashioned. Italy’s economic system is largely based on family structures and the elderly who don’t want to give up power. Corruption(腐败) is also a big problem that simply won’t go away.

The Italian government is aware of the problem and says it must create new opportunities for its younger generation. But even if it starts working on a new style economy right away it may take years before things in Italy really change. The government has already passed laws which will make it easier for doctors, lawyers and other academics to start a career in Italy.

Many economic experts claim that Italy is doing a lot for its older generation but very little for its youth. For example, it spends little on housing, childcare but a lot on pensions.

小题1:Some people are leaving Italy mainly because they _____ .

A.want to get a job

B.want to travel abroad

C.prefer working abroad

D.no longer love their country小题2:The Italian government _____ .

A.is blind to the problem of emigration

B.encourages young Italians to go abroad

C.has taken some measures to change the situation

D.promise to offer more jobs to young Italians soon小题3:Many economic experts think that the Italian government should _____ .

A.do more for its youth

B.try to improve its economy

C.stop its youth from going abroad

D.solve the problem as soon as possible小题4:What problem is Italy facing?

A.Most of its laborers are old.

B.There aren’t any truly talented youngsters.

C.The government officials’ attitude is old-fashioned.

D.People with power are doing illegal and dishonest things.小题5:Which of the following might be the best title for the passage?

A.Italian emigration history

B.More care for old Italians

C.Young Italians are leaving Italy

D.The influence of economic difficulty

题型:填空题

有一房间的墙壁,刚用熟石灰粉刷过.房间主人为了使墙壁快点干燥,就在房间里生了一个炭火盆,结果发现墙壁反而更潮湿了.写出有关化学方程式是______;原因是______.

题型:填空题

当今世界不动产登记制度主要包括()三种类型。

A.契约登记制

B.财产登记制

C.权利登记制

D.义务登记制

E.托伦斯登记制

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