题目

阅读理解 Modem inventions make our life easier and more interesting than before. Let's take a look at some inventions. A new kind of enzyme (酶) Scientists in Britain and the United States have, found a new kind of enzyme that eats plastics. With its help, plastics can be turned into smaller parts and go away quickly. It can stop plastics from being burned everywhere. Scientists believe that it can solve the problem of plastic pollution in the future. Social robot Can robots talk to us like humans? Jibo, a robot made in US, can talk with you. The robot has a big, round head and a bi如图甲的电路中，电源电压保持不变，闭合开关后，滑片P由b端滑到a端，电压表示数U与电流表示数I的变化关系如图乙，当滑片P置于b端时，变阻器消耗的功率为    W．通过探究（如采用计算特殊值进行比较等方法）可以得出：当滑片P由b端滑到a端的过程中，变阻器所消耗功率的变化规律是    （逐渐增大/逐渐减小/先增大，后减小）．