皮皮学，免费搜题
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【单选题】
下面哪一位是的老师?()A.
外尔
B.
C.
冯·卡门
D.
冯·布劳恩
拍照语音搜题，微信中搜索"皮皮学"使用
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皮皮学刷刷变学霸
举一反三
【单选题】When an invention is made, the inventor has three possible courses of action open to him: he can give the invention to the whole world by publishing it, keep the idea secret, or patent it. A granted p...
A.
It is necessary for an inventor to apply for a patent before he makes his invention public.
B.
A patent holder must publicize the details of his invention when its legal period is over.
C.
one can get all the details of a patented invention from a library attached to the patent.
D.
When a patent becomes out of effect, it can be re-patented or extended if necessary.
【简答题】A．Courses for doctors. B．Courses for businessmen. C．Courses for reporters. D．Courses for lawyers.
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