只用组内溶液相互混合就能鉴别出来的一组溶液是
A．K2CO3、H2SO4、HNO3、BaCl2
B．Na2CO3、HCl、Na2SO4、HNO3
C．HNO3、HCl、NaCl、Ag NO3
D．Na2SO4、NaOH、CuSO4、NaCl
答案：A
在做物质的鉴别题时，主要分为两类：一类是选项中有带色的离子，首先鉴别，然后再区别其他的物质，另一类就是类选项中的四种物质都是无色的，就需要借助表格进行鉴别，不管哪种，在鉴别时每组出现的现象不能完全相同，此种鉴别题相对比较麻烦；
A、
| K2CO3 | H2SO4 | HNO3 | BaCl2 | |
| K2CO3 | --------------- | ↑ | ↑ | ↓ |
| H2SO4 | ↑ | ------------ | 无现象 | ↓ |
| HNO3 | ↑ | 无现象 | ---------- | 无现象 |
| BaCl2 | ↓ | ↓ | 无现象 | -------------- |
阅读下列短文，根据所读的内容在文章后的表格中填入恰当的单词。注意表格中的每个空格只填1个单词。 注意：每个空格只填1个单词 Although most of us have been learning English for more than three years or even more, we still doubt whether every one of us has already known how to learn English well. Some students still think that learning English is just to remember new words, phrases, grammar rules and some sentence structures. It seems if we do so, we can have a good knowledge of English. We must make sure that things are not always what they seem to be. Now imagine how we learn our mother tongue well. We learn it well by communicating with the people around us all day long. So we think it’s not difficult for us to learn our mother tongue. Why do we think it is hard to learn English well? We all know that learning English usually takes place in schools and there are few opportunities to communicate with other speakers of the language. As a result, some think that learning English is slow and much difficult. It’s because we spend less time learning and practicing it than doing our mother tongue. The following may help us in some way. We should gain confidence and we must be brave enough to speak English before others. Don’t be afraid of losing our faces while talking with others in English. We must make a long and careful study plan. Once we do it, we must take pains to continue learning English every day. Think about what we have done and decide to study English harder than ever. Finally we should take every opportunity to practice speaking English as often as possible. Title: ___小题1:___ to Learn English Well
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