问题 问答题 简答题

什么是有平衡无扰动切换?

答案

参考答案:

由手动操作状态切换到自动调节器控制状态,或相反切换,由于手动操作器与调节器输出不相等,切换过程给控制阀造成干扰称为有扰动切换,为消除这一扰动,在切换之前先调整手动操作器输出使之等于调节器输出,然后从自动控制切换手动操作器控制,或在切换前将调节器的输出调整得等于手操作器输出,然后从手动控制切换到调节器控制,这样切换不造成扰动。但切换前必须调整手操器或调节器使二者输出相等,这个调整过程称为平衡,有平衡无扰动切换即切换前必须人为地调整手操器或调节器输出,使二者输出相等,然后再切换才免于扰动的切换方法。

阅读理解

Music died here last spring, or rather, it was killed by members of the school committee who ignored the importance of music and drama as part of the high-school curriculum.

The committee decided that teaching students how to take a standardized test is more important than a curriculum in which students can explore their interests in the arts as well as academics. Because the school system is running out of funding, it needs to make sure that students pass the mastery test or even more money will be lost. If students fail the state standardized test, it is not the fault of drama and music classes— they are failing because the “ academic” classes are not sufficient.

It is painful to think of how many students will be discouraged from singing, acting, and playing instruments because school programs are no longer offered. Many families cannot afford private music lessons, and many potential musicians and artists may not find their calling if they are not exposed to it in school. The fact that the school committee thinks the arts are not worth the investment will certainly make some students believe the arts are not worth their time or support and the cycle will continue.

Teaching for a test does not shape students into complete, well rounded people. It blocks the natural sense to create and express feelings through art— there is more to life than the analytical thinking that math and English provide. What happens after a test? Sure, a student might graduate, but they will have limited knowledge — certainly not a good preparation for the real world.

小题1:Music and drama are not included in the high-school curriculum mainly because________.

A.the school committee pays no attention to them

B.the school is afraid of losing financial support

C.the students are not interested in both of them

D.the state standardized test is more important.小题2:Which of the following is TRUE according to the passage?

A.The sufficiency of the classes determines students’ performance in the mastery test

B.students can be musicians and artists only if they can afford private music lessons

C.The school committee completely influences students’ attitude towards the arts

D.Quite a few students are discouraged from music and art in today’s school system.小题3:We can learn that music and art can ________.

A.make students round-shaped people in future

B.provide students with analytical thinking

C.motivate students in creativity and expression

D.prevent students graduating from high school小题4:The best title of the passage can be ________.

A.Who Killed Music and Drama?

B.Can Curriculum Go Without Music?

C.Why is Music So Important?

D.How To Prepare For the Real World?

单项选择题