问题 单项选择题

具有生产效率高等优点的碾压机械开行方式是______。

A.进退错距法
B.圈转套压法
C.进退平距法
D.圈转碾压法

答案

参考答案:B

解析: 碾压方式主要取决于碾压机械的开行方式。碾压机械的开行方式通常有:进退错距法和圈转套压法两种。进退错距法操作简便,碾压、铺土和质检等工序协调,便于分段流水作业,压实质量容易保证。圈转套压法要求开行的工作面较大,适合于多碾滚组合碾压。其优点是生产效率较高,但碾压中转弯套压交接处重压过多,易产生超压。当转弯半径小时,容易引起土层扭曲,产生剪力破坏,在转弯的四角容易漏压,质量难以保证。

阅读理解

阅读理解。

     Modern inventions have speeded up people's lives amazingly. Motor-cars cover a hundred miles in

little more than an hour, aircraft cross the world inside a day, while computers operate at lightning speed.

Indeed, this love of speed seems never-ending. Every year motor-cars are produced which go even faster

and each new computer boasts (吹嘘) of saving precious seconds in handling tasks.

     All this saves time, but at a price. When we lose or gain half a day in speeding across the world in an

airplane, our bodies tell us so. We get the uncomfortable feeling known as jet-lag; our bodies feel that they

have been left behind in another time zone. Again, spending too long at computer results in painful wrists

and fingers. Mobile phones also have their dangers, according to some scientists; too much use may

transmit

harmful radiation into our brains, a consequence we do not like to think about.

     However, what do we do with the time we have saved? Certainly not relax, or so it seems. We are so

accustomed to constant activity that we find it difficult to sit and do nothing, or even just one thing at a time.

Perhaps the days are long gone when we might listen quietly to a story on the radio, letting imagination take

us into another world.

     There was a time when some people's lives were devoted simply to the cultivation of the land or the care

of cattle. No multi-tasking there; their lives went on at a much gentler pace, and in a familiar pattern. There is

much that we might envy about a way of life like this. Yet before we do so, we must think of the hard tasks

our ancestors faced: they farmed with bare hands, often lived close to hunger, and had to fashion tools from

wood and stone. Modern machinery has freed people from that primitive existence.

1. The new products become more and more time-saving because _____.

A. the manufacturers boast a lot

B. time is limited

C. the prices are increasingly high

D. our love of speed seems never-ending

2. What does "the days" in Paragraph 3 refer to?

A. Simple life in the past.

B. Imaginary life.

C. Times of inventions.

D. Time for constant activity.

3. What is the author's attitude towards the modern technology?

A. Critical.

B. Optimistic.

C. Objective.

D. Negative.

4. What does the passage mainly discuss?

A. The present and past times.

B. Modern technology and its influence.

C. Imaginations and inventions.

D. Machinery and human beings.

单项选择题