For example, if an inventor obtains a patent on a new kind of umbrella, the inventor (or anyone else to whom he sells his patent) can legally prohibit other companies from making and selling this kind of umbrella, but can not prohibit customers who have bought this umbrella from the patent owner from reselling the umbrella to third parties.
例如，如果一个发明家获得一种新型伞子的专利权，发明家（或任何其他人向他买下他的专利的人）可以合法地禁止其他公司生产和销售这种伞子，但不能禁止客户从专利权所有人买下这把伞子后再卖给第三方客户。