问题 问答题 简答题

集中式控制系统有什么优缺点?

答案

参考答案:

在计算机控制与管理系统发展的初期,几乎全是集中式系统。这是有客观原因的,因为当时计算机的价格比较昂贵,购置一台要较多的投资,人们总希望它能承担较多的任务,尤其是当时一些大型生产装置或过程的测量控制点比较多,需要集中在操作室由一两个人全面监视,这样集中式控制就显出一定的优越性,在管理方面也有类似需要集中、汇总的情况。

但是在使用了一段时间后,发现了许多缺点,一是由于集中式系统主机过于庞大,所以可靠性较差,一旦失效影响全局,造成很大损失;二是在同一台计算机上完成不同的任务,无效开销太大,反应不及时;三是缺乏扩展的灵活性;四是如果被控设备或信息源距主机过远,所用线缆过多过长会造成投资的大量增加。

阅读理解

阅读理解

      When we talk about stars, especially women stars, it seems that they are always young, pretty and own attractive body shapes. But recently a Britain’s Got Talent(英国达人)star Susan Boyle has changed our views completely.

      Simon Cowell, one of the organizers of the talent show spoke of his surprise over Ms Boyle’s voice. “This lady came up, and I’m thinking, ‘This will take five seconds and I can go to have a cup of tea.’ That changed when she began to sing I Dreamed a Dream from Les Miserables. She knew we were going to have that reaction(反应)and just to see that look of satisfaction on her face midway through - it was one of my favorite moments,” Cowell said.

      The performance was posted online and before long, the 47-year-old Scottish woman has been famous all over the world.

      Speaking from her home in Scotland, Ms Boyle said that she hadn’t thought of changing her appearance. She said that her friend helped her with make-up. “I mean, it’s meaningless.” She added.

      Ms. Boyle also spoke of the reason she first began to explore her musical talents. “ I was kind of slow at school, so getting something like singing was a good way of hiding behind that and therefore it built my confidence.’’

1. Susan Boyle had a look of satisfaction on her face when she was singing because ________.          

A. she was confident of her singing

B. she was satisfied with the organizers

C. she was pretty and in good shape

D. she sang the song I Dreamed a Dream from Lea Miserables  

2. According to the passage, which is NOT true?

A. It was the musical talents that built Susan's confidence.

B. Susan Boyle was not good at her lessons when at school.

C. Susan Boyle became famous because of her appearance.

D. Simon Cowell didn't think Susan Boyle a good singer at the time sight.

3. What can we learn from Susan Boyle’s success?

A. It’s never too old to learn.  

B. It’s easier to succeed at the age of 47.

C. If you have a dream, keep trying to make it come true!  

D. If you are not able to study well, to be a singer instead.

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