A排列顺序
B性质与用途
①节水程度由低到高:漫灌、滴灌
②地壳中元素含量由低到高:硅、氧
③一个分子中原子总数由大到小:NH3、CH4
①氧气能供给呼吸:医疗急救
②氮气化学性质稳定:做保护气
③稀有气体通电发不同颜色的光:电光源
C化学史
D物质的鉴别
①最早用定量方法研究空气成分:拉瓦锡
②发现元素周期律:张青莲
③相对原子质量测定:门捷列夫
①蒸馏水和酒精:闻气味
②双氧水和蒸馏水:用二氧化锰
③二氧化碳和氮气:用燃着木条
A:A
B:B
C:C
D:D
关于压岁钱的使用,下列做法正确的是( )
It is Saturday morning. My father is ____ the car. I am ____ him. My mother is ____ ____ in the kitchen. Helen is ____ the living room. She is ____ the floor. Where is Tim? What is he doing now? Tim is in his ____ .He is ____. Ben's dog is sleeping too.
下列物体在运动中,受平衡力的是( )