The technological barriers appeared formidable because there were serious doubts as to【51】 wh______these fiber components could ever be produced economically enough, but the market potential was very significant.【52】______(consequence) , research and development activity expanded rapidly, and a number of important issues were【53】re______during the early 1970s. During the middle and late 1970s, the rate of progress towards marketable products accelerated as the emphasis【54】______(shift) from research to engineering. Fibers with losses【55】app______the Rayleigh limit of 2 dB/km at a wavelength of 0. 8 μm were produced.
By 1980 improvement in component performance, cost, and reliability led to major commitments on the part of telephone companies.
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第1题
A.In the early 1990s
B.In the late 1970s
C.In the early 1950s
D.In the early 1940s
第3题
第4题
A.In the early 1990s
B.In the late 1970s
C.In the early 1950s
D.In the early 1940s
第5题
A、after W W I
B、in the early 1950s
C、during W W II
D、in the 1960s
第6题
The statement "In my fridgeless fifties childhood, I was fed well and healthily. " (Line 1, Para. 2) suggests that______.
A.the author was well-fed and healthy even without a fridge in his fifties
B.the author was not accustomed to using fridges even in his fifties
C.there was no fridge in the author's home in the 1950s
D.the fridge was in its early stage of development in the 1950s
第7题
A.The Beat Generation
B.The Lost Generation
C.The Angry Young Men
D.Black Mountain Poets
第8题
A、It has a strong beat and simple melodies.
B、It mainly based on the black rhythm, blues and white country music.
C、It’s a type of popular music developed in the early 1950s in America.
D、It is merely played by black musicians, and no white musicians play it.
第9题
A) the author was well-fed and healthy even without a fridge in his fifties
B) the author was not accustomed to using fridges even in his fifties
C) there was no fridge in the author’s home in the 1950s
D) the fridge was in its early stage of development in the 1950s
第10题
The statement “In my fridgeless Fifties childhood, I was fed well and healthily.” (Line 1, Para. 2) suggests that ________.
A) the author was well-fed and healthy even without a fridge in his fifties
B) the author was not accustomed to using fridges even in his fifties
C) there was no fridge in the author’s home in the 1950s
D) the fridge was in its early stage of development in the 1950s
第11题
In the 1950s, the pioneers of artificial intelligence (AI) predicted that, by the end of this century, computers would be conversing with us at work and robots would be performing our housework. But as useful as computers are, they're nowhere close to achieving anything remotely resembling these early aspirations for humanlike behavior. Never mind something as complex as conversation: the most powerful computers struggle to reliably recognize the shape of an object, the most elementary of tasks for a ten-month-old kid.
A growing group of AI researchers think they know where the field went wrong. The problem, the scientists say, is that AI has been trying to separate the highest, most abstract levels of thought, like language and mathematics, and to duplicate them with logical, step-by-step programs. A new movement in AI, on the other hand, takes a closer look at the more roundabout way in which nature came up with intelligence. Many of these researchers study evolution and natural adaptation instead of formal logic and conventional computer programs. Rather than digital computers and transistors, some want to work with brain cells and proteins. The results of these early efforts are as promising as they are peculiar, and the new nature-based AI movement is slowly but surely moving to the forefront of the field.
Imitating the brain's neural network is a huge step in the right direction, says computer scientist and biophysicist Michael Conrad, but it still misses an important aspect of natural intelligence. "People tend to treat the brain as if it were made up of color-coded transistors", he explains, "but it's not simply a clever network of switches. There are lots of important things going on inside the brain cells themselves. " Specifically, Conrad believes that many of the brain's capabilities stem from the pattern recognition proficiency of the individual molecules that make up each brain cell. The best way to build an artificially intelligent device, he claims, would be to build it around the same sort of molecular skills.
Right now, the option that conventional computers and software are fundamentally incapable of matching the processes that take place in the brain remains controversial. But if it proves true, then the efforts of Conrad and his fellow AI rebels could turn out to be the only game in town.
The author says that the powerful computers of today ______.
A.are capable of reliably recognizing the shape of an object
B.are close to exhibiting humanlike behavior
C.are not very different in their performance from those of the 50's
D.still cannot communicate with people in a human language
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