问题 问答题 论述题

采煤机无链牵引机构使用较多的形式有哪几种?各有何应用特点?

答案

参考答案:(1)齿轮—销轨型

其特点是传动力矩大,适用于中厚煤层,销轨维护简单,不适底板起伏。

(2)滚轮—齿轨型

其特点是牵引机构的牵引力大,可用于大倾角煤层工作。

(3)强力链轮—链轨型

其特点是牵引机构有较好的挠性,能适应底板不平的工作面,但是其牵引力小,速度快。

(4)复合齿轮齿条型

其特点是机构齿部粗壮,强度高,寿命长,交错齿轮啮合运行平稳。

阅读理解

任务型阅。

    阅读短文,并按要求完成1-5题。

     Computers and internet are very important to us now. People like scientists, teachers, writers and even

students use computers to do many work. But how many of us know the history of the computers and

internet. The internet was set up in the 1960s. At that time computer couldn't do much work. They were

very large and expensive. Very few people were interested in them and knew how to use them.

      At first the internet was only used by the government, but in the early 1970s, universities, hospitals and

banks were allowed to use it, too. However, computers were still very expensive and the internet was difficult

to use. Today computers are smaller and cheaper. And the internet is easier to use. Since they are useful, many

people like to use them, even at home. Today it is easy to get on-line and it is said that millions of people use the

internet every day. Sending e-mails is more and more popular among young people. The internet has now

become one of the most important parts of people's life.

     1.  题判断正误("T"表示正确,"F"表示错误);2 题完成句子;3-4题简略回答问题;5 题将文中划

线句子译成汉语.

( )1. Many people use the computers and internet before 1960s.  

2. Most people don't know _____________the computers in the 1960s.

3. When was the internet set up?

_________________________________________________________________________

4. Was the internet used widely before 1970s?

________________________________________________________________________

5.________________________________________________________________________

问答题 简答题