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问题 选择题

根据“绿色化学”的思想，某化学家设计了下列化学反应步骤：

该方案的主要目的是为了制备

A．HBr

B．CaO

C．H2

D．Hg

答案

答案：C

依据绿色化学中关于绿色化学的要求是，即在获取新物质的化学反应中充分利用参与反应的每个原料原子，所以每一个反应的生成物只要能是其它反应的反应物则就可循环使用，分析知反应①的两种产物分别可为②③提供产物，反应②的生成物溴化汞可为③提供反应物，氢气未被重新利用，反应③的生成物可用于④①的反应物，反应④中的生成物汞可用于反应②，氧气没有被重新使用，故在整个的反应中最后剩余的物质是氢气与氧气，分析选项可得答案

故选C

单项选择题

拟除虫菊酯引起的中毒表现为（）

A.神经系统症状

B.肝功能损伤

C.肾功能损伤

D.血液系统损伤

E.胃肠道症状
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单项选择题

How should one invest a sum of money in these days of inflation (通货膨胀) Left in a bank it will hardly keep its value, however high the interest rate is. Only a brave man, or a very rich one, dares to buy and sell on the Stock Market. Today it seems that one of the best ways to protect your savings, and even increase your wealth is to buy beautiful objects from the past. Here I am going to offer some advice on collecting antique clocks, which I personally consider are among the most interesting of antiques.
I sometimes wonder what a being from another planet might report back about our way of life. "The planet Earth is ruled by a mysterious creature that sits or stands in a room and makes a strange ticking sound. It has a face with twelve black marks and two hands. Men can do nothing without its permission, and it fastens its young round people’s wrists so that everywhere men go they are still under its control. This creature is the real master of Earth and men are its slaves."
Whether or not we are slaves of time today depends on our culture and personality, but it is believed that many years ago kings kept special slaves to tell the time. Certain men were very clever at measuring the time of day according to the beating of their own hearts. They were made to stand in a fixed place and every hour or so would shout the time. So it seems that the first clocks were human beings.
However, men quickly found more convenient and reliable ways of telling the time. They learned to use the shadows cast by the sun. They marked the hours on candles, used sand in hourglasses, and invented water-clocks. Indeed, any serious student of antiques should spend as much time as possible visiting palaces, stately homes and museums to see some of the finest examples of clocks from the past.
Antique clocks could be very expensive, but one of the joys of collecting clocks is that it is still possible to find quite cheap ones for your own home. After all, if you are going to be ruled by the time, why not invest in air antique clock and perhaps make a future profit

The underlined phrase "stately homes" in Paragraph 4 means ______.

A．state-owned houses

B．houses in very good condition

C．grand houses open to the public

D．houses where statesmen meet regularly
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