A. a country's wealth depends on many factors
B. the U.S.A. is one of the wealthiest countries in the world
C. the Sahara Desert is a very poor region
D. natural resources' are an important factor in the wealth or poverty of a country
23. The word 'civil'(line 14) refers to wars to wars that are .
A. long -lasting
B. fought between one part of a country and another
C. short but frequent
D. carried out according to the international laws governing warfare
24. The main idea of the fourth paragraph is that .
A. Britain is dependent upon trade
B. A country's wealth lies in what it can manufacture
C. Britain manufactures more than it needs for home consumption
D. The wealth of a country can be increased by manufacturing goods trade with other countries
25. The word 'margin' as used in line 22 means .
A. the space at the side of the page
B. the edge
C. the amount earned but not needed for living
D. any money deposited in a savings account
Some day there may be a robot that takes the drudgery out of housework and even cleans windows, but how soon such a robot will emerge is anybody's guess. Mr.Joseph Engelberger, President of Unimation, Inc. which makes industrial robots, says a workable domestic robot might take shape by the late 1980s, but Mr. Ben Skora, an amateur robot builder now working on his second creation, predicts household robots in about fifty years, and the Director of Stanford University's Artificial Intelligence Laboratory, Dr. John McCarthy, says domestic robots are anywhere from five to five hundred years away.
Although robots are already widely used in industry -from welding car parts to handling explosives -the gap between the industrial robot and a domestic one is great, according to Dr.McCarthy. Closing the gap will require an intellectual break -through.
'Take the task of clearing the table and washing the dishes,' he suggested 'The robots will have to be able to discriminate between rubbish and dishes that should be washed and, meanwhile, not trip over the dog or baby on the floor on its way to the dishwasher.'
He said that the robot, which he defines as a general purpose physical action machine that is automatically controlled, probably will not end up looking like a human being .Instead the robot might have a central 'brain' that controls a whole army of bodies, like a staff of servants, each as -signed to a specific duty.
Mr.Engelberger thinks the domestic robot is right around the corner, just waiting for an eco -nomic boost to help it over the remaining technological hurdles. He expects the household robot to be modeled after an industrial forebear.
'But the person who wants a robot will have to build this world around it,' Mr. Engelberger said.' for example, a fellow building a house might spend twenty -five per cent more to have it "robotized". Such a "robotized" house probably would have to be free of stairs and other encumbrances that could trip a near -sighted robot, would provide special sockets for it to plug into, and would contain a "pantry" where the robot's brain and tools would be stored.'
He added that the robot would probably have to see (by means of a sophisticated TV camera) and have a sense of touch to do housework. It could even be programmed for some superhuman tasks, such as acting as a smoke -detector that would alert a family to a fire and then fight it.
The robot created by Mr. Skora is a long way from fighting fires, but Arok (which is Mr.Skora's name spelt backwards without the's ) can vacuum the carpet, take out the rubbish and bring in the mail by following programs in his computer brain. For the more complicated tasks, such as taking the dog for a walk, Mr. Skora commands Arok through a radio -transmitter as he watches the robot from a window.' No computer in the world could work out when a dog is ready to stop,' He pointed out .
Mr. Skora says that Arok was conceived more as an experimental toy than a convenience. In fact, Arok doesn't save any time around the house and demands supervision for the simplest chore.
26.The main idea of the first paragraph is that we .
A. will definitely have domestic robots one day
B. will not have domestic robots for a very long time
C. will have domestic robots in the fairly near future
D. have no way of knowing when we may have domestic robots
27.the writer uses the word 'creation' (1.5) because .
A. Mr. Skora is an amateur robot builder
B. It was Mr. Skora's second robot
C. Mr. Skora was making something that had never been made before
D. The robot was an experiment
28.Dr McCarthy believes that there is a big difference between an industrial robot and a domes -tic one because the domestic robot .
A. will be more intellectual
B. must be capable of performing more functions
C. must be automatically controlled
D. will not look like a human being
29.Mr. Engelberger thinks that the domestic robot will be .
A. similar to an industrial robot
B. very expensive to buy
C. entirely new
D. able to go anywhere
30.Mr. Skora describes Arok as an experimental toy because it .
A. is controlled by a radio transmitter
B. is a convenience
C. serves no useful purpose
D. can perform only simple chores
Blind people usually possess one advantage over other people who can see: their sense of hearing is far more acute. Sounds which most others would miss can carry a great deal of information to a sightless person. For instance, teams of blind children can enjoy fast -moving games of soccer with a bell inside the ball and a new hand -held ultrasonic device to guide them. And that sound -location system could help to build up an even more complete sound picture to guide them. And that sound -location system could help to build up an even more complete sound picture of a blind person's surroundings.
Bats, whose sight is poor, use a sound -location system to help them avoid obstacles in the dark. They send out pulses of sound waves, pitched at 50,000 cycles per second, far above the limits of the human ear, which can hear sounds up to frequencies of about 20,000 cycles per second. As the echoes bounce back off obstacles such as trees and walls, the bats are able to take appropriate action. The sound is emitted by an ultrasonic torch, shaped like a double -barreled version of a normal electric torch. It works in a similar way to a sonar unit on a warship or submarine.
The unit's transmitter sends out pulses of ultrasonic waves at the same frequency as the bat, and the receiver picks up the returning echoes. Because these are still above the frequency at which the human ear can pick them up, the echoes are filtered through circuits which turn them into clearly audible "bleeps" before passing them into headphones.
This means that a person holding the torch can point it ahead of him and "scan "the area for obstacles over a range of about 25 ft. If there are no return echoes coming through the headphones, then there is nothing in the way.
If echoes do come back, then the closer the obstruction the faster the succession of bleeps and the deeper the pitch of each bleep. With practice the torch could help a blind person to lead a more normal life -without needing a constant companion to guide him .Experienced operators of the torch system claim they can distinguish grass from bushes ,tress, posts and kerbstones.
But before blind people can be helped to feel really independent, the system needs to be more streamlined. At present ,the experimental ultrasonic torch requires a shoulder bag to carry the batteries, cables for the power supplies and earphones, in addition to the torch itself. But miniaturization of electronic equipment is making such rapid progress that it should not be long before the whole set -up can be reproduced in a form small enough to fit into a pair of spectacles. The transmitter and power supplies, with all the circuitry, would be packed into the bridge -piece above the nose. The sending and receiving sensors would be in the "lenses". And the filtered bleeps would be passed on to the wearer through the earpieces, as with present -day hearing -aid spectacles.
This would mean that scanning one's surroundings would become instinctive. The wearer would face in the direction he wanted to check, and lift or lower his head just as a sighted person would.
31.Compared with those with normal vision, blind people possess .
A. greater sensitivity to sound
B. a more vivid imagination
C. a greater sense of smell
D. an ability to distinguish every tiny sound
32.The attempt to help blind people to see with sound .
A. was similar to the sound location system of the bats
B. led to a product that sent out sound waves of about 20,000 cycles per second
C. was experimented on a submarine
D. turned out be a failure
33.Experienced operators of the torch system claim that .
A. they are able to distinguish an object's color
B. they can visualize an entire 25-foot area
C. they can function as effectively as if they had normal vision
D. they can distinguish grass from bushes ,trees ,posts and kerbstones
34.The author predicts that in the future ultrasonic devices could be .
A. worn as an earpiece
B. worn as eyeglasses
C. carried in one's pocket
D. strong enough to detect frequencies above 50,000 cycles per second
35.The word "instinctive" in the last paragraph means that with the future ultrasonic device, .
A. the bind will appear like the sighted people when scanning his surroundings
B. the blind will scan his surroundings automatically
C. the blind will have to turn his face while walking
D. the blind will be able to lift or lower his head while walking
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