在某介质中形成一列简谐横波,该横波上有相距4m的A、B两点,下图所示为A、B两质

题型:计算题

问题:

在某介质中形成一列简谐横波,该横波上有相距4m的A、B两点,下图所示为A、B两质点的振动图象,若这列波的波长大于2m,求:这列波的波速。

考点:机械波的形成和传播
题型:计算题

下列基本医疗保险基金准予支付的药品目录的是()

A.西药和中药饮片

B.西药和中成药

C.中成药和中药饮片

D.中药饮片

E.中药材

题型:计算题

What picture do you have of the future? Will life in the future be better, worse of the same as now? What do you hope about the future?

Futurologists predict that life will probably be very different in 2050 in all the fields of activity, from entertainment to technology. First of all, it seems that TV channels will have disappeared by 2050. Instead, people will choose a programme from a menu and a computer will send the programme directly to the television. Today, we can use the World Wide Web to read newspaper stories and see pictures on a computer thousands of kilometers away. By 2050, music, films, programmes, newspapers and books will come to us by computer.

In what concerns the environment, water will have become one of our most serious problems. In many places, agriculture is changing and they are growing fruit and vegetables to export. This uses a lot of water. Demand for water will increase ten times between now and 2050 and there could be serious shortages. Some futurologists predict that water could be the cause of war if we don’t act now.

In transport, cars will run on new, clean fuels and they will go very fast. Cars will have computers to control the speed of the car and there won’t be any accidents. Today, many cars have computers that tell the drivers exactly where they are. By 2050, the computer will control the car and drive it to your destination. On the other hand, space planes will take people half way around the world in two hours. Nowadays, the United States Shuttle can go into space and land on Earth again. By 2050, space planes will fly all over the world and people will fly from Los Angels to Tokyo in just two hours.

In the field of technology, robots will have replaced people in factories. Many factories already use robots. Big companies prefer robots — they do not ask for pay rises or go on strike, and they work 24 hours a day. By 2050, we will see robots everywhere — in factories, schools, offices, hospitals, shops and homes.

In particular, medicine technology will have conquered many diseases. Today, there are electronic devices that connect directly to the brain to help people hear. By 2050, we will be able to help blind and deaf people see again and hear again and scientists will be able to produce clones of people and decide how they look, how they behave and how much intelligence they have. Scientists will be able to do these things — but should they?

小题1:. What may happen in the field of entertainment in the future?

A.The programme made by yourself may be sent to TV.

B.A computer may choose TV programmes for you.

C.You may choose the channels from the menu in a computer.

D.What to broadcast on TV is decided by yourself.小题2:. After reading Paragraph 3, we can know _______.

A.we should take measures to save water from now on

B.fruits will be more and more expensive

C.people will be short of supplies of vegetables

D.planting will need much less water in the future小题3:. ________ is the main factor that makes driving much safe in the future

A.Good traffic condition

B.A good knowledge of driving skill

C.The role played by computer

D.The use of new fuel in cars小题4:. The following statements are wrong EXCEPT ________ according to the text.

A.The future world will be controlled by robots.

B.People won’t be blind or deaf in the future.

C.Fewer and fewer workers are needed in the future in factories.

D.Scientists have the right to clone people of different kinds.

题型:计算题

回收期的主要缺点是:()。

A.无法度量风险的大小

B.忽略了回收期之外的现金流

C.没有考虑货币的时间价值

D.B和C是对的

题型:计算题

在门控单元的硬件发生故障或系统存储器的软件缺失时,红色LED()。

A.恒亮

B.不亮

C.闪烁

D.亮一段时间后熄灭

题型:计算题

电动钻井的电传动系统主要由()组成。

A.SCR和MCC

B.SCR或VFD和MCC

C.VFD和MCC

D.SCR和VFD

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