And similarly old crystal radio sets and more recently modern radio frequency identification (RFID) tags, increasingly used in shipping and as antitheft devices, are powered purely by radiowaves.

同样，老式晶体管收音机，以及日益普及于航运及防盗装置上的，更新式的现代无线射频识别技术(RFID)，都是仅仅从无线电波中获取能量。

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Parents were quizzed about the types and frequency of the food and drink their children consumed when they were three, four, seven and eight and a half years old.

在这些儿童三岁、四岁、七岁和八岁半时，研究人员向孩子的父母询问了孩子所摄入的饮食的种类，以及隔多长时间进食。

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Parents were quizzed about the types and frequency of the food and drink their children consumed when they were three, four, seven and eight and a half years old. They were marked on a.

在这些儿童三岁、四岁、七岁和八岁半时，研究人员向孩子的父母询问了孩子所摄入的饮食的种类，以及隔多长时间进食。

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David slays Goliath, but now this old plot is repeating with accelerating frequency.

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Experts point to the smaller supply of work by women from certain periods after all they're called Old Masters, not Old Mistresses which limits the frequency of sales and holds down prices.

WSJ: In the Art World, Women on the Verge

For example, rather than purchase expensive ultra-efficient motors, low cost opportunistic additions to old fans and pumps such as variable frequency drives and demand controls can deliver equal energy savings at a fraction of the cost.

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