A、He could renew it. B、He could destroy it at random. C、He could sell it and make a lot of money. D、He could do nothing since th

(16) The American patent system, provided for in the Constitution, was designed to encourage the creation and use of new technology. An inventor would describe an invention, both in writing and with drawings, and submit the description with a model to a government official. This was a big improvement from the past when patents were submitted directly to the Secretary of State! Now, if the invention was judged to be new and useful, the official would give the inventor a patent. The patent meant that for 14 years, later changed to 17 years, the inventor owned the new invention. Inventors could license their ideas to manufacturers or just use them themselves. (17) The government would not issue any other patent for the same idea, and the inventor could sue anyone who used the patented idea without paying the owner of the patent for permission to use it! A useful patent meant that the inventor could make a lot of money. In exchange for this governmental protection, the government published the patent specifications, which provide enough information so that other people could understand the invention—thus adding to the general available technological knowledge. (18) And at the end of the 14 years, anyone could use the invention for free. (19) The idea behind the patent system was twofold: it would increase the amount of technology, by providing a way for people to make money out of new ideas, and it would make new technology widely available, by publicizing ideas that might otherwise be kept as trade secrets.
16. What is the speaker mainly talking about?
17.What could the inventor do if the idea was used by someone without paying money?
18.What could the owner of the patent do to protect his patent after 14 years?
19.How did the patent system increase the amount of technology?