他用大衣袖子把碎屑掸掉。He cleaned the flakes away with his coat sleeve.地上满是他刻木雕时落下的碎屑。The floor was covered with shavings from his wood carvings.你削铅笔时, 会削下许多碎屑.When you sharpen a pencil, you make chips....
方法: 用溴代及胺化反应合成了四甲基吡嗪衍生物.METHODS: The target compound was prepared by the bromination and amination reaction.用溴—甲醇溶解Al_2O_3, 其回收率在91%以上.If Al 2 O 3 is dissolved by Br 2 - CH 3 OH, its Recovery rate is above 91 %.用溴比用氯时产出率...