A:用氯酸钾和二氧化锰制氧气时用排水法收集后,应从水中撤出导管后再停业加热
B:在氢气还原氧化铜停止加热后,还要继续通一会儿氢气
C:实验室制备CO气体必须在通风橱中进行
D:蒸馏操作时应在混合液中加入沸石
放爆竹和礼花时,若你在一旁观看,最好张开嘴或捂住耳朵、闭上嘴.这种做法主要是为了( )
A visit to the moon is____ ____a fantastic dream.
To _______ somebody to do something means to make somebody do something they don't want to do.
物质X可发生下列所示的两个反应,则X可能是( )①X+碱→盐+H2O ②X+金属氧化物→盐+ H2O