Stern also studies and observes the behaviour of babies.斯特恩还研究观察婴儿的行为。He observes carefully but says little.他总是仔细观察,很少说话.He observes keenly but says very little.他观察敏锐,却很少发言....
本文介绍了以氟硅酸钠、纯碱为原料生产晶体氟化钠的工艺,并对操作条件作了详细的说明.A method of producing crystal sodium fluoride with sodium fluosilicate and sodium carbonate is introduced.在2008年6月2日, 氟化钠被自?成为新条目候选之候选条目.At 2 June, 2008, Sodium Fluoride was recom...