题目

阅读理解 Scientists in Michigan have developed a forest fire alarm system. It can not only detect when a fire begins but also call for help. This battery-free device hangs like an ornament(装饰品) in a tree and harvests all the energy it needs from the natural swinging of branches. Such a sensor could watch the woods for a decade without human attention. “For forest fire monitoring, you don't need high amounts of energy,” notes Cao Changyong, an engineer at Michigan State University who led the team behind the new device. It recharges itself about every 10 minutes with just enough power to take a measurement. That's plenty of time, Cao says, “to generate sufficient energy.” There's an obvious need for fast monitoring of remote forests. Every year fires burn millions of acres in the United States. Early detection also can save lives right now. Forest fires are spotted from satellites or fire towers. Neither, Cao notes, is as fast or low-cost as tree-hanging sensors would be. Cao's group faced some challenges in creating its new sensors. For example, these have to produce enough power to survey the forest and send out a signal and that power source has to be durable. To tackle the problems, they decided to convert(转化) mechanical motion into electricity. The device to do this is known as a TENG, short for triboelectric nanogenerator. Scientists have explored TENGs as one way to harvest energy from the natural world, including harvesting energy from impacts on tabletops, falling rain, and even keyboards. The new TENG for forest use produces a current when a tree branch swings. That current is small, yet enough to power a thermometer(温度计) to detect the temperature changes signaling a fire. Cao says his team's new model has not yet been tested over long time periods in the real world, but the device is ready. All he needs now is the money to build more of them. （1） What is special about Cao's sensor? A . It is self-powered. B . It is shaped like a branch. C . It can be used as a charger. D . It keeps power for about a day. （2） What advantage does Cao's sensor have over satellites and fire towers? A . It can work for a longer time. B . It can monitor remoter forests. C . It can make quicker detection. D . It can be operated more easily. （3） What does the underlined part “do this” in paragraph 4 refer to? A . Turn mechanical energy into electrical power. B . Send out a signal when a fire breaks out. C . Detect temperature changes in forests. D . Collect electrical energy from nature. （4） What can be the best title for the text? A . Forest Fires Data Collected by Battery-Free Devices B . Forest Fires Predicted by Tree-Hanging Sensors C . A New Forest Fire Alarm System Arousing Forest Protection D . A New Forest Fire Alarm System Powered by Trees 答案： A C A D

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