问题 问答题 简答题

为什么说迟缓率不能等于零?

答案

参考答案:

⑴实际的调节系统迟缓率不可能做到等于零。因调节系统各机构在运行中总存在摩擦等阻力,油动机滑阀总要有过封度,使系统感受到转速变化到调节汽门开度变化存在迟缓。

⑵从理论上分析,迟缓率等于零的调节系统是不稳定的,因为这将造成调节过分灵敏,使调节汽门处在不停的动作之中。尤其对于液压式调节系统,保持一些微小的迟缓率,对改善调节性能是有益的。液压式调节系统的调节油压不可避免地存在着油压波动,它将使调节汽门窜动。这也就是错油门必须有一定的过封度,使其抵消油压波动的影响,避免调节汽门窜动的道理。

单项选择题
阅读理解

Englishmen speak British English and Americans speak American English. A student is learning to speak British English. He often asks himself, “Can Americans understand me when I speak British English?” Learners often ask “What’s the difference between British English and American English?”Certainly there are some differences between British and American English. The Englishmen say “Have you a pen?” While Americans say “Do you have a pen?” The pronunciation is sometimes different. Americans often sound “r” in words like “bird” and “hurt”. The British speakers don’t sound the “r” in these words. There are differences in spelling. For example, “colour” and “neighbour” are British while “color” and “neighbor” are American. These differences in grammar, pronunciation and spelling are not important, however. For the most part, British and American English are the same language. When Englishmen and Americans are talking with each other, they don’t need an interpreter(翻译). Maybe some day they need, but not now.

小题1:Between British and American English, _______.

A.the greatest difference is in spelling

B.there are differences in many ways

C.people can’t understand each other

D.students don’t know the difference小题2:When a student is asking himself “Can Americans understand me when I speak British English?” it shows that_______.

A.he wants to learn American English

B.he doesn’t like British English

C.he hasn’t spoken to any American so far

D.he is going to spend more time on American English小题3:43. The differences between British and American English are not important because______

A.everyone knows the differences   

B.people talk to each other very often

C.Englishmen and Americans get along well

D.British English and American English are the same language小题4:“Have you a pen” and “Do you have a pen?” show a difference in______

A.grammar

B.spelling

C.pronunciation

D.listening小题5:At the end of the passage the writer wants to tell us _______.

A.British and American English will be two different languages some day

B.Englishmen and Americans will never need an interpreter while talking

C.there will be no more differences between British and American English

D.the differences between British English and American English will grow larger