问题 选择题

欲除去氢氧化钠溶液中的少量杂质氢氧化钙,可以选用的试剂(  )

A.氢氧化钾溶液

B.碳酸钠溶液

C.氯化钡溶液

D.稀盐酸

答案

A 氢氧化钾溶液既不与氢氧化钠溶液反应,又不与氢氧化钙溶液反应,因此A不正确;

B 碳酸钠溶液只与杂质氢氧化钙反应,并且反应后生成的是碳酸钙白色沉淀和氢氧化钠溶液,不会加入新的杂质,因此B正确;

C 氯化钡溶液既不与氢氧化钠溶液反应,又不与氢氧化钙溶液反应,因此C不正确;

D 稀盐酸与氢氧化钠溶液和氢氧化钙溶液都反应,因此D不正确;

故答案为:B

阅读理解

English nowadays is widely used in science, business, the media and popular culture. For example, 80% of e-mails on the internet are in English. But where will English be at the end of the 21st century?

One view is that English is going to become even more important as a global language, being most widely used in trade and media while some other languages will become less important or just disappear. Another view is that English is already breaking up into several separate languages. There are already dictionaries of the “New Englishes”, such as Australian English, full of words that a British English speaker would not recognize.

Hopefully, neither of these things will happen. Although different varieties of English will continue to develop around the world, standard English will survive for international       communication. However, it is impossible for one language to totally control the world. Already, other languages are fighting back against the control of English on the net. Governments around the world are also starting to protect smaller languages and recognize the importance of keeping a variety of cultures and languages. English will probably stay in control for a long time, but it certainly won’t become the only language in the world.

小题1: According to the situation, how many people do you think speak English now?

A.200 million

B.300 million

C.500 million

D.a billion小题2:At present, what is the most important language in the world?

A.Chinese

B.English

C.French

D.German小题3:What is the best title of the passage?

A.The Change of English

B.Different Varieties of English

C.The Future of English

D.The Cause of English Change

单项选择题