图是汽油机的剖面图．如图表示的是____ 冲程．它将____ 能转化成____ 能．

在香港海洋公园的游乐场中，有一台大型游戏机叫“跳楼机”．参加游戏的游客被安全带固定在座椅上，由电动机将座椅沿光滑的竖直轨道提升到离地面40m高处，然后由静止释放．座椅沿轨道自由下落一段时间后，开始受到压缩空气提供的恒定阻力而紧接着做匀减速运动，下落到离地面4.0m高处速度刚好减小到零，这一下落全过程经历的时间是6s．求：（取g=10m/s²）

 同一品种的结球甘蓝，在北京栽培，长成的叶球约重l﹣3千克，引种到西藏后，叶球的重量普遍增加，最大的竞达6.5千克，当再引种回北京，长成的叶球又是约重l﹣3千克，此现象说明了甘蓝叶球大小这一性状（　　）

   I am Bill Jones. I am a teacher of English. My wife is Linda Jones. She is a nurse. We have a daughter and a son. We have many friends.
Look! These are my friends. This is Mr. Black. He is a worker. He works in a shoe factory He makes shoes there. That’s Mrs. Black. She is a worker on a farm near here. The girl is their daughter. She is a student. She is thirteen. The boy is their son. He is a young soldier（战士）. His name is Carl Black.