When an invention is made, the inventor has three possible courses of action open to him: he can give the invention to the world by publishing it, keep the idea secret, or patent (申请专利) it．

　　A granted patent is the result of a bargain struck between an inventor and the state, by which the inventor gets a limited period of monopoly (垄断) and publishes full details of his invention to the public after that period terminates．Only in the most exceptional circumstances is the lifespan of a patent extended to alter this normal process of events．

　　The longest extension ever granted was to Georges Valensi; his 1939 patent for color TV receiver circuitry was extended until 1971 because for most of the patent's normal life there was no color TV to receive and thus no hope of reward for the invention．

　　Because a patent remains permanently public after it has terminated, the shelves of the library attached to the patent office contain details of literally millions of ideas that are free for anyone to use and, if older than half a century, sometimes even repatent．Indeed, patent experts often advise anyone wishing to avoid the high cost of conducting a search through live patents that the one sure way of avoiding violation of any other inventor's right is to plagiarize a dead patent．

Likewise, because publication of an idea in any other form permanently invalidates further patents on that idea, it is traditionally safe to take ideas from other areas of print．Much modern technological advance is based on these presumptions of legal security．

Anyone closely involved in patents and inventions soon learns that most “new” ideas are, in fact, as old as the hills．It is their reduction to commercial practice, either through necessity or dedication, or through the availability of new technology, that makes news and money．The basic patent for the theory of magnetic recording dates back to 1886．Many of the original ideas behind television originate from the late 19th and early 20th century．Even the Volkswagen rear engine car was anticipated by a 1904 patent for a cart with the horse at the rear．

1．The passage is mainly about ________．

[　　]

A．an approach to patents

B．the application for patents

C．the use of patents

D．the access to patents

2．Which of the following is TRUE according to the passage?

[　　]

A．When a patent becomes out of effect, it can be repatented or extended if necessary．

B．It is necessary for an inventor to apply for a patent before he makes his invention public．

C．A patent holder must publicize the details of his invention when its legal period is over．

D．One can get all the details of a patented invention from a library attached to the patent office．

3．George Valensi's patent lasted until 1971 because________．

[　　]

A．nobody would offer any reward for his patent prior (在前的) to that time

B．his patent could not be put to use for an unusually long time

C．there were not enough TV stations to provide colour programmes

D．the colour TV receiver was not available until that time

4．The underlined word plagiarize most probably means ________．

[　　]

5．From the passage we learn that________．

[　　]

A．an invention will not benefit the inventor unless it is reduced to commercial practice

B．products are actually inventions which were made a long time ago

C．it is much cheaper to buy an old patent than a new one

D．patent experts often recommend patents to others by conducting a search through dead patents