题目内容
用量爪卡紧物体时,用力不能太大,否则会使测量不准确,并容易损坏卡尺。卡尺测量不宜在工件随意滑动,防止量爪面磨损。
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卡尺使用完毕,要擦干净后,将两爪零线对齐,检查零点误差有无变化,再小心放入卡爪专用盒内,存放在不干燥的地方。
砝码除了放在盒内相应的空位或天平盘上还可以放在软布上。
天平室要经常敞开门窗通风,以防室内过于潮湿。
In the last 500 years, nothing about people---not their clothes, ideas, or languages---has changed as much as what they eat. The original chocolate drink was made form the seeds of the cocoa tree by South American Indians. The Spanish introduced it to the rest of the world during the 1500’s. And although it was very expensive, it quickly became fashionable. In London shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600, the Spanish brought it fromPeruto Europe, where it soon was widely grown.Irelandbecame so dependent on it that thousands of Irish people starved when the crop failed during the “Potato Famine” of 1845-6, and thousands more were forced to immigrate toAmerica.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction.Brazilis now the world’s largest grower of coffee, and coffee is an important crop inColombiaand other South American countries. But it is native toEthiopia. It was first made into a drink by Arabs during the 1400’s.According to an Arabic legend, coffee was discovered when a goatherd named Kaldi noticed that his goats were attracted to the red berries on a coffee bush. He tried one and experienced the “wide-awake” feeling that one-third of the world’s population now starts the day with.According to the passage, 1 has changed the most in the last 500 years.In London, some 2 still exist today.Irish people starved during the “Potato Famine” because they were 3 .Coffee originally came from 4 .According to an Arabic legend, 5 discovered coffee.
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