_____、_____。_______、_______。_______(用“<”、“>”、“=”表示)。___________。___________。依次是________,________。4结束实验的操作是:先________,再_________。____________________________。仪器的名称________、________。制备氧气的优点_________。___________。_______________________________。_______________________________。___________。选用________和________。中酒精灯的作用是_________________。__________。(选填“串联”或“并联”)的。