题干

学习了声音的相关知识后,小明同学做了以下小结,请你在横线上为小明填上空缺。
⑴悠扬的笛声是空气____ 产生的;
⑵声音在水中的传播速度____ (大于/等于/小于)在空气中的传播速度;
⑶在月球上,声音不能传播的原因是____ ;
⑷如图所示,甲、乙是两种声音的波形图,由图形可知:图____ 是噪声的波形;

⑸在繁华闹市区设立的噪声监测器测定的是声音的____ (响度/音调/音色/频率)。某时刻该设备的显示屏上显示58.60的数字,这个数字的单位是____ ;若此时有一辆大卡车路过此地,显示屏上显示的数据将____ (增大/减小);噪声监测设备____ (能/不能)减弱噪声的强度;
⑹中考期间,考场附近“禁鸣喇叭”,这是在____ (声源处/传播途中/人耳处)减弱噪声。噪声也是一种能源,最近科研人员开发出一种T恤衫,它能在噪声环境下发电,把____ 能转化为电能,为随身携带的小电器及时充电。

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答案(点此获取答案解析)

振动,大于,真空不能传声,乙,响度,dB,增大,不能,声源处,声

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B

    Researchers say they have created a new super-tough material in the laboratory. It is stronger, lighter and costs less than steel. But the new material is not a product of high technology. It is wood. Researcher Liangbing Hu says that it can compete with some of the world's strongest materials or even replace steel.

    The product is called Super Wood. It doesn't require any special raw, unprocessed material. That means the cost of the product will be relatively low.Hu said, “We can start with very cheap wood, and also very fancy, expensive wood. But in the end, we get very similar performance.”

    Super Wood is made by partially removing a natural polymer called lignin(木质素). Hu explained, “Lignin is like glue to hold all the parts together in natural wood. To be able to densify(增密)the wood completely, some of the lignin has to be removed. “Strong chemicals are put on the wood to remove about half of its lignin. Then, after being left in extreme heat and pressurized for a day, the treated wood is ready.

    The wood is strong enough to build automobiles, airplanes, wind turbines and more. Researchers are finding many new ways to use wood, including creating batteries and see-through wood and paper.Hu said, “Wood has been existing on Earth for more than a million years. And human beings have been using wood for furniture, construction for more than 10 thousand years. And the more we worked on this material, we realized, we have never fully exhausted the potential of this amazing material.”