一混合气体,可能由氢气、甲烷、一氧化碳和二氧化碳四种气体中的一种或几种组成,为了

题型:填空题

问题:

一混合气体,可能由氢气、甲烷、一氧化碳和二氧化碳四种气体中的一种或几种组成,为了解该混合气体的组成,进行了下面的实验:

①将混合气体通过澄清的石灰水,未见出现浑浊现象;

②将混合气体点燃,并在火焰上方罩一只冷而干燥的烧杯,烧杯壁上有水珠出现.烧杯倒转后,注入少量澄清的石灰水,振荡,发现烧杯内的石灰水变浑浊;

③将混合气体通过灼热的氧化铜,试管壁上也有水珠出现,但尾气未能使澄清石灰水出现浑浊.

仔细分析上面的实验现象后,对该气体的组成你能得出哪些结论?

______.

考点:设计实验和科学探究二氧化碳的检验和验满
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1912年2月15日,即清帝宣布退位三天后,孙中山率临时政府文武员赴明孝陵,祭奠明太祖朱元璋。这一事件反映了当时孙中山革命思想中的

A.民族主义思想

B.民权主义思想

C.民生主义思想

D.实业救国思想

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转基因技术就是对某一物种具有特别性状的基因进行分离,并把它移植到另一物种上去,从而使这一物种具有组合基因。然而转基因技术也会带来负面影响。从下列选项中选出不是由转基因生物可能带来的弊端[ ]

A.对生物多样性的影响,如抗除草剂作物的产生会破坏农田的生物多样性

B.使近亲野生物种具有抗性基因,可能会变成“超级杂草”

C.转基因生物的食品加工带来食品污染

D.转基因生物的大规模繁殖导致生态入侵

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The findings of a new survey have American professors talking about the good old days—when A's were a lot tougher to earn.

Sites like RateMyProfessors.com make it easy for students to find a class taught by a professor who is known as an "easy grader".A recent survey by Kaplan Test Prep found that 46 percent of the more than 1,200 students polled admitted to using the site for just such a purpose.

"Our research shows that many of today's college students are looking at multiple factors when picking out courses: overall teacher quality that will result in a good learning experience, but also instructors who don't like to award a lot of C's and D's," said Jeff Olson, vice president of research at Kaplan Test Prep.

"While it makes sense that students would choose kinder graders, it also helps explain the recent popularity of grade inflation(膨胀)."

Grade inflation is seen by many professors as poisoning the learning environment.Some, like former Duke University professor Stuart Rojstaczer, are righting it head-on.

On his website, Gradelnflation.com, he releases an annual list of schools where grade inflation is the worst.

This year, he decided to name the schools where grades were inflated the least.He praised, for example, Princeton University, as well as Purdue University, where the average GPA has remained around 2.8 for over 30 years.

"Purdue doesn't even seem to know that grade inflation exists in the US," Rojstaczer says."Ignorance is bliss(极大的幸福)."

68.From the passage we may know that Kaplan Test Prep is most probably _____

A.an institute             B.a professor 

C.a vice president        D.a course

69.Grade inflation is spreading because _____.

A.it's poisoning the learning environment

B.instructors intend to improve their overall teaching quality

C.many instructors adapt to the students' expectations

D.students get easy access to sites like RateMyProfessors.com

70.The passage suggests that _____.

A.universities will employ hard graders

B.if we want to be happy, we should be ignorant

C.A's are becoming easy to earn at most US universities

D.professors and instructors should give students higher grades

71.The writer tends to _____.

A.favor easy graders                B.see grade inflation as unavoidable

C.oppose Kaplan Test Prep         D.miss the days when A's were hard to earn

题型:填空题

传统的细胞分型法是用来判断HLA哪个抗原()。

A.HLA-A

B.HLA-B

C.HLA-C

D.HLA-D

E.HLA-E

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东莞这边申请用住房公积金贷款买房吗?

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