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问题 问答题 简答题

电化学分析仪为什么一般不调校零点？

答案

参考答案：

电化学分析仪一般测量ppm级氧含量，所分析的样品气中氧含量正常情况下只有400ppm左右，而我平常所用零点气为管道氮，其中氧含量都有几十ppm，如果这样校正了零点，会使仪表示值产生较大影响。

听力题

Today some people call Amsterdam the“City of Bicycles”because it is a city which is flat and convenient(方便的)for bicycles.

In the 1960s, a group of cycling fans had an i  46 . They believed that it would be better for everybody if o  47  bicycles were allowed in the city centre. They were hopeful that this would help to save energy, reduce pollution and provide free public transport. The group p  48  hundreds of bicycles white and placed them in public places around Amsterdam for people to use.  A  49  was allowed to take them and use them for short journeys, whether he was a local or a foreigner. Wherever someone finished a journey, they would l  50  the bike there for someone else to use. The problem was that it didn’t work –t  51  took all the bicycles within weeks!

H  52 , more than thirty years later，the“white bike”is back in town---this time with a computer chip(芯片)to r  53  its every move! There is a  54  less traffic in central Amsterdam. Thanks to the good ideas of lots of people, like the cycling fans in the 1960s, many people around the world have been enjoying city centre streets w  55  cars for many years.

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单项选择题

包豪斯成立于（）年，学校建在德国的魏玛，它的第一任校长是格罗佩斯

A.1880

B.1900

C.1919

D.1925
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