问题 问答题 简答题

齿轮传动具有哪些特点?

答案

参考答案:(1)效率高。在常用的机械传动中,以齿轮传动的效率最高。

(2)结构紧凑。在同样的使用条件下,齿轮传动所需的空间尺寸一般较小。

(3)工作可靠,寿命长。设计、制造正确合理,使用维护良好的齿轮传动,工作可靠,寿命可达一二十年,这也是其他机械传动所能比拟的。

(4)传动比稳定。传动比稳定往往是对传动的一个基本要求。

阅读理解

How often do you use your car? Can you use your car less often? Do you know the following facts in the UK?

·About 50% of all car journeys are just for fun.

·Over 80% people go to work by car.

·25% car journeys are under two miles.

·70% car journeys are under five miles.

WALKING & CYCLING

Instead of using the car for short journeys, why not walk or ride a bicycle? Walking is the most popular form of exercise—it’s healthy and it can save money. If you work nearby, try walking or cycling instead of driving. Walking your children to school gives them valuable road experience.

BUSES

Bus companies are using new buses: some run on new fuelswhich produce less pollution; some have easier access(通路)for disabled and old people. There are special traffic lanes (行车道)to make bus journeys easier. So do something to help solve the pollution problem----let the bus take you to work and your children to school.

TRAINS

All car journeys, long or short, can be hard work. For some trips, it is wiser to take the train. Leave your car at home and walk, cycle or take a bus to and from the station. Train travel is fast, safe and comfortable. Train tickets are not always expensive.

小题1:How many of car journeys are just for fun in the UK?

A.25%.

B.About 50%.

C.70%.

D.Over 80%.小题2:The writer believes that _____________________ can give children valuable road experience.

A.walking to school

B.traveling by train

C.taking new fuel buses

D.having car journeys for fun小题3:What does the writer think of traveling by train?

A.Tiring.

B.Exciting.

C.Terrible.

D.Comfortable.

单项选择题 A1/A2型题