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The First Navigational Lights In the New World the first navigational lights were probably lanterns hung at harbor entrances. The first lighthouse was put up by the Massachusetts Bay Colony in 1716 on little Brewster Island at the entrance to Boston Harbor. Paid for and maintained by "light dues" levied on ships, the original beacon was blown up in 1776. By then there were only a dozen of so true lighthouses in the colonies. Little over a century later, there were 700 lighthouses. The first eight lighthouses erected on the west coast in the 1850’s featured the same basic new England design: a Cape Cod dwelling with the tower rising from the center or standing close by. In New England and elsewhere, though, lighthouses reflected a variety of architectural styles. Since most station A. The first lantern wicks were developed there. B. It was tile headquarters of the United States Lighthouse Board. C. Many of the tallest lighthouses were built there. D. The first lighthouse in North America was built there. [判断题]混凝土振捣的时候，为使振捣更到位，可以将振捣器直接放到钢筋和模板上。
[判断题] 燃烧产物对灭火工作有利方面为:在一定条件下有阻燃作用;为火情侦察提供依据。( )
A.正确 B.错误 [单选题]用于解析域名的协议是______。
A. HTTP B. DNS C. FTP D. SMTP [简答题]区分特定物与种类物的法律意义何在？
[单选题]（）时，禁止就地倒闸操作和更换熔丝。
A.大风 B.雷电 C.大雨 D.大雪 [判断题]当车厢连挂后，锁紧装置会形成一个三角形形状，这样可以将牵引载荷均匀地分布在两个钩锁装置上（ ）
A.正确 B.错误 [填空题]土壤是植物生长发育的（）。
[单项选择]慢性粒细胞白血病白细胞计数一般为（）。
A. （10～30）×109/L B. （100～300）×109/L C. （30～50）×109/L D. （300～500）×109/L E. （1000～3000）×109/L [简答题]>试述分光光度法的工作原理?
我来回答: 提交
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