问题 问答题 论述题

试分析机组产生过速的原因是什么?

答案

参考答案:

当电力系统发生故障时,使带负荷的机组突然甩掉负荷。由于导水叶不能瞬时关闭,减小机组进水量有一定延时,在此延时内,水轮机转速可能增高(20%-40%)额定转速。如此时调速器又有故障,使导水叶不能关闭,则机组转速上升很快。当转速升高到某一整定值以上,则机组出现过速事故。

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