21 silicon rubber

uel tank ________．

A.Steel or aluminum

B.Sandwich style fibreglass with a natural rubber core

C.Copper-nickel or copper silicon alloys

D.Any or all of the above

ns(秘鲁人)that when a cut was made in the outside skin of a rubber tree, a white liquid like milk came out, and that from 【21】______ a sticky mass of rubber might be made. This rubber is 【22】______ when warm, so that it is possible to give it any 【23】______ . The Peruvians made the 【24】______ that it was very good for keeping out the wet. Then in the early 1800's, the Americans made use of it for the first time. First they made overshoes to 【25】______ their feet dry. Then came a certain Mr. Mackintosh, who made coats of cloth covered with natural rubber. From that day to this we have been coating cloth with rubber as Mr. Mackintosh 【26】______ , and our raincoats are still named after 【27】______ .

These first rubber overshoes and raincoats were all soft and sticky 【28】______ summer, and hard and inelastic (没有弹性的)in the winter 【29】______ it was cold. 【30】______ the rubber we have today is soft and elastic, it is very strong 【31】______ in the warmer summer and the colder winter. This was made possible by a man 【32】______ Goodyear. After many 【33】______ , he found that nitric acid(NHO3) made the rubber 【34】______ better, but it is not hard and strong enough. Then strange thing 【35】______ . A friend of his, Nicholas Hayward, had the 【36】______ in his sleep that rubber might be made hard and strong if mixed 【37】______ sulphur and put in the sun. Goodyear put this idea to the test, and saw that it did have more or less the desired 【38】______ though somewhat less than more. The only effect it had was on the outside of the rubber. 【39】______ is common knowledge now that the way to make rubber hard and strong is by heating it with sulphur. It took Goodyear four more years to find this heating method. When 【40】______ he did it, he had nothing at all. Everything of the smallest value had been used to get money, even his sons' school-books.

【21】

A．those

B．this

C．these

D．them

se trees do not【21】rubber. They are,【22】, made of rubber. Mr Joe Dynamo, a spokesman for Los Angeles【23】council, explained the reasons. He said:

"These【24】are representative of our virtual society. We have polystyrene grass on our golf【25】. We have non-milk powder【26】our coffee. We【27】copies in plastic of old wooden furniture. We have fiberglass tombstones.【28】shouldn't we have trees made of rubber？"

"At 50 miles an hour,【29】motorist will see any difference. And our preservation【30】will be lower. You give the trees an annual rinse with detergent, and【31】them off twice a year. We【32】a lot of money because transplanting, pruning, weeding and leaf-collection are all【33】And we have a 60-year【34】guarantee on each plant. This is rationalization at【35】best."

(41)

A．invent

B．do

C．produce

D．create

根据下面内容，回答题：

Los Angeles has planted 2，000 rubber trees down the middle of one of its main streets．These trees do not 21 rubber．They are，22， made of rubber．Mr．Joe Dynamo， a spokesman for Los Angeles 23 council， explained the reasons．He said:

"These 24 are representative of our virtual society．We have polystyrene grass on our golf 25．We have non-milk powder 26 our coffee．We 27 copies in plastic of old wooden furniture．We have fiberglass tombstones.28 shouldn"t we have trees made of rubber？"

"At 50 miles an hour，29 motorist will see any difference．And our preservation 30 will be lower．You give the trees an annual rinse with detergent， and 31 them off twice a year．We 32 a lot of money because transplanting， pruning， weeding and leaf-collection are all 33 And we have a 60-year 34 guarantee on each plant．This is rationalization at 35 best， "

材料题请点击右侧查看材料问题 查看材料

A.invent

B.do

C.produce

D.create

？Read the article below about MOO．

？Choose the correct word to fill each gap frOm A，B，C or D．

？For each question(21-30)，mark one letter(A，B，C or D)on your Answer Sheet．

One of the most visible locational decisions on．a high technology firm was made by the Microelectronics and Computer Technology Corporation(MCC)．A joint venture of a dozen major computer and semi-conductor firms，MCC was founded to do research (21) advanced level technologies such as new generations of supercomputers，artificial intelligence and robotics． (22) a consortium created in 1982 by several firms，it had no home base or locational inertia，and began its search for a site by examining 57 cities across the country．The cities made polished sales pitches to lure the firm's eventual 400 engineers and scientists．The four finalists in the chase-Atlantis，Austin，San Diego and Raleigh-Durham，in the Research Triangle area of North Carolina， (23) ．was particularly noted for high tech activity．

When Austin was choosen。its attractions to MCC were widely analysed by other would-be Silicon Valleys．Austin，the state capital，iS the site of the main campus of the University of Texas，a school that (24) among the top twenty in the country in research funding．The university's reputation，state commitments of further support，and the city's proven quality of life attractiveness (25) high tech people were the deciding factors．Austin and the State of Texas added to these attractions a package of financial and other incentives，including a favorable lease on land in the university's research park and subsidized mortgages (26) ．relocating employees．

(27) return Austin had got not only the MCC．In the typical snowballing manner of high tech areas，several other companies have decided to move research (28) other advanced technology facilities there．Lockheed Missiles and Space Company，3M Corporation，and Motorola are among the firms which have added to theagglomeration of technical workers there， (29) the expense of cities like Minneapolis and Phoenix，where the companies have other facilities．As a matter of fact，the entire 100 mile corridor between Austin and San Antonio is nicknamed“Silicon Gulch”．San Antonio is the site of several computer biotechnology and electronics companies． (30) the“Gulch”will rival the San Francisco Bay and Boston regions in high technology will depend on its ability to spawn a succession of new firms as technology advances and changes．

(21)

A．of

B．on

C．about

D．to

Although 【21】______ circuits made computers smaller, the processing units still consisted 【22】______ a number of circuits on separate chips. In 1971, an engineer working for Intel realized that a 【23】______ of circuits commissioned for an electronic calculator could all be put 【24】______ one chip, and that the resulting device could be used 【25】______ a general-purpose "computer on a chip". The result was the Intel 4004 -- the world's first microprocessor. Physically, it consisted of a silicon chip in a protective ceramic capsule, with a set of metal pins sticking 【26】______ that connected it to other components in whatever 【27】______ it controlled. It 【28】______ 2,300 transistors, 【29】______ 60,000 operations per second, and could be used for any device -- including computers and robots -- that required a "brain" for accepting 【30】______ and following a program of 【31】______ to produce an output. Within five years, many very powerful microprocessors had 【32】______ .The invention of microprocessors 【33】______ the stage for the arrival of the microcomputer, or personal computer (PC)-- an affordable machine for 【34】______ The first PCs, in kit form, appeared in the mid 1970s, and by the mid-1980s machines such as the Apple Macintosh and those based 【35】______ a PC first 【36】______ by IBM in 1981 were popular throughout the world. The success of these machines led to an explosion of software, in 【37】______ a range of spreadsheet, word-processing, graphic, educational, and games programs. Since the 1980s, a number of strong-intertwined themes have 【38】______ the computer revolution forward, including a continuing increase in the processing power and decrease in the size and cost of PCs; a switch of emphasis from 【39】______ to linked machines, as evidenced by the growth of local area networks and the Internet; and the spread of computer applications into virtually every 【40】______ of home and business life.

【21】

A．integral

B．comprehensive

C．integrated

D．general

as good as paper: cheap enough to be pasted on to wails and billboards, clear enough to be read in broad daylight, and thin and flexible enough to be bound as hundreds of flippable leaves to make a book. Over the past few years they have got close. In particular, they have worked out how to produce the display itself, by sandwiching tiny spheres that change colour in response to an electric charge inside thin sheets of flexible, transparent plastic. What they have not yet found is a way to mass-produce flexible electronic circuitry with which to create that charge. But a paper just published in the Proceedings of the National Academy of Sciences suggests that this, too, may be done soon.

The process described by John Rogers and his colleagues from Bell Laboratories, an arm of Lucent Technologies, in New Jersey, and E Ink Corporation, in Cambridge, Massachusetts, starts with E Ink's established half-way house towards true electronic paper. This is based on spheres containing black, liquid dye and particles of white, solid pigment. The pigment particles are negatively charged, so they can be pushed and pulled around by electrodes located above and below the sheet.

The electrodes, in turn, are controlled by transistors under the sheet. Each transistor manipulates a single picture element (pixel), making it black or white. The pattern of pixels, in turn, makes up the picture or text on the page. The problem lies in making the transistors and connections. Established ways of doing this, such as photolithography, use silicon as the semiconductor in the transistors. That is all right for applications suck as pesters. It is too fragile and too expensive, though, for genuine electronic paper—which is why cheap and flexible electronic components are needed.

For flexibility, Dr. Rogers and his colleagues chose pentacene as their semiconductor, and gold as their wiring. Pentacene is a polymer whose semiconducting properties were discovered only recently. Gold is the most malleable metal known, and one of the best electrical conductors. Although it is pricey, so little is needed that the cost per article is tiny.

To make their electronic paper the researchers started with a thin sheet of Mylar, a tough plastic, that was coated with indium-tin oxide (ITO), a transparent electrical conductor. To carve this conductor into a suitable electric circuit, they used an innovation called microcontact printing lithography. This trick involves printing the pattern of the circuit on to the ITO using a rubber stamp. The "ink" in the process is a solvent-resistant chemical that protects this part of the ITO while allowing the rest to be dissolved.

From the first paragraph of the passage, we can learn that an electronic display ______.

A．can be made as good as paper

B．is cheap enough to be pasted on to walls and billboards

C．will be as thin and flexible as paper

D．is difficult to be created in the form. of flexible electronic circuitry