阅读理解词句猜测之单词短语猜测专项训练-2023届高三英语二轮复习

单词和短语猜测类 [2021广东深圳、汕头、潮州、揭阳名校高三联考]A 语篇类型：说明文 主题语境：人与社会 When you walk with a backpack, do you know how the things inside move from side to side? Now scientists have figured out how to tap into that movement to produce electricity. Picture a pendulum （钟摆） fixed to a backpack frame and stabilized with springs on either side. The pack’s weight is attached to the pendulum, so the pendulum swings from side to side as you walk. Then a machine is driven by that swinging movement, and spits out electrical currents to charge a battery. Volunteers carried the pack while walking on a running machine and wore masks to measure the flow of O2 and CO2. Walking with the slightly swinging 20-pound load, the device （设备） did not significantly affect the volunteers’ metabolic （新陈代谢的） rate compared to when they carried the same weight fixed in place. In fact, the energy-harvesting pack reduced the forces of acceleration they’d feel in a regular pack, which might mean greater comfort for a long hike. And the device did produce a steady trickle （涓流） of electricity. If you up the load to 45 pounds, the swing of the pack could fully charge a smart phone only after 12 hours. The details are in the journal Royal Society Open Science. The device produces electricity from human movement and has been identified as a workable solution to providing a renewable energy source for portable electronic devices. It is particularly useful for those who work in remote areas, as these people often carry a lot of weights in a backpack for their exploration. But here’s a real conundrum:the energy-harvesting device currently weighs five pounds. The researchers say that’s about four pounds too many to be a smart alternative to batteries. So they hope that more research lets them lighten the load, to ensure the pack charges you up without weighing you down. 1. What does Paragraph 2 mainly talk about?( ) A. How the device works. B. What the device looks like. C. Who the device is designed for. D. Why sc