三、Please use 40 to 80 words to summarize the following article in English, do not copyany sentence in the excerpt.（20 分）  Last February during his Fireside Hangout, President Obama explained that patent trolls(known more formally as Patent Assertion Entities, or PAEs) “don’t actually produceanything themselves. They’re just trying to essentially leverage and hijack somebodyelse’s idea and see if they can extort some money out of them.” This type of abusivepatent litigation is a major problem.  It’s also important to know what we’re not talking about here. We aren’t trying to makeit harder to pursue legitimate intellectual property rights, or vigorously defend validpatents. Indeed, the United States has the best intellectual property protections in theworld, and our system rightly ensures that these innovators are compensated for theircreativity. The problem is when rogue companies make a business model out ofexploiting and abusing the system, using it not to protect invention but to bring frivolouslawsuits to extract settlements from companies trying to serve American consumers. Badpatents in the system (such as those issued with broad or vague language) onlycompound the problem, and the issue extends far beyond any one industry.