鸡蛋壳的主要成分是碳酸钙.老师在课堂上做了个趣味实脸,将鸡蛋放入盛有120毫升稀

题型:问答题

问题:

鸡蛋壳的主要成分是碳酸钙.老师在课堂上做了个趣味实脸,将鸡蛋放入盛有120毫升稀盐酸的烧杯中(鸡蛋的密度大于稀盐酸的密度),可以看到鸡蛋先下沉,一会又上浮,到液面时又下沉,如此反复.该实验中发生的化学反应方程式是______.浮力改变是鸡蛋下沉后又上浮的直接原因,而造成浮力改变的主要原因是______.除此主要原因外,引起浮力改变的原因还有______(假设在反应的过程中,鸡蛋、溶液体积和温度不变).

小明对该实验很感兴趣,他也将同样的鸡蛋,放入实验室常见的酸溶液中,但见鸡蛋下沉后却并不上浮,你猜测这其中的原因可能是______,或是______.

考点:盐的性质化学反应方程式的书写文字表达式酸的性质
题型:问答题

     阅读理解

     When you are reading something in English, you may often meet with a new word. What's the best

 way  to know it?

     You may look it up in the English-Chinese dictionary. It will tell you a lot about the word: the

 pronunciation, the Chinese meaning and how to use the word. But how can you know where the word is

 thousands of English words? How to find it in the dictionary both quickly and correctly?

      First, all the English words are arranged (安排) in the letter order. In the dictionary you can first see

  the words beginning with letter A, then B, C, D…. That means, if there are two words "desert" and "pull", "desert" will be certainly before "pull". Then if there are two words both beginning with the same letter, you may look at the second letter. Then the third, the fourth…

1. This passage is about _____.

    A. new words in writing

    B. different dictionaries

    C. the best way of reading

    D. using an English-Chinese dictionary

2. In the dictionary you may not find _____.

    A. how to pronounce the word

    B. the spelling of the word

    C. who used the word first

    D. how to use the word

3. In an English-Chinese dictionary, the last word _____.

    A. begins with Z

    B. begins with A

    C. is a short one

    D. is not often used

4. Which group of words is in the right order in an English-Chinese dictionary?

    A. perhaps, produce, plenty 

    B. straight, subject, surprise

    C. century, center, business

    D. foreign, entrance, headache

5. In the passage the writer tries to tell us that _____.

    A. we have to use a dictionary when we read something in English

    B. an English-Chinese dictionary can tell us everything about a word   

    C. an English-Chinese dictionary can help us a lot in our English study

    D. all English-Chinese dictionary are the same

题型:问答题

矿山开采通常分为露天、()和海洋开采三种形式。

题型:问答题

医学模式转变在医学伦理学方面的重要意义表现在( )

A.有助于医生思维方式的转变

B.提高全社会对生命和健康的认识

C.实现了在更高层次上对人的健康的全面关怀

D.推进祖国医学的发展和提高

E.促进医生知识结构的合理性和全面素质的提高

题型:问答题

电信管理网中主要使用的协议是( )。

A.SNMP

B.RMON

C.CMIS和CMIP

D.LMMP

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人生价值有三部分组成,其中居于核心地位的是()。

A、社会价值和自我价值

B、社会价值

C、人格价值

D、自我价值

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