如图是纪念抗战胜利70周年阅兵式上20架直升机组成“70”的字样，好长一段时间队形不变，甚为壮观，队形不变时，飞机之间相对____ （运动、静止）；观礼人听到的飞机声是通过____ 传播而来．
“验证机械能守恒定律”的实验中．如图甲是打点计时器打出的一条纸带，选取其中连续的计时点标为A、B、C…G、H、I，对BH段进行研究．
①已知打点计时器电源频率为50Hz，则纸带上打相邻两点的时间间隔为____．
②用刻度尺测量距离时如图（乙），读出A、C两点间距为____ cm，B点对应的速度vB=____m/s（保留三位有效数字）；
③若H点对应的速度为vH，重物下落的高度为hBH，当地重力加速度为g，为完成实验，要比较 12vB2 与____大小（用字母表示）．
“低碳生活，从我做起！”请仔细阅读下列材料，找出以下五种“低碳”行为产生的直接效应。
①15个苹果，平均放在3个盘子里，每盘放____个。
②15个苹果，每盘放5个，可以放____盘。
Mr. Jones teaches history. He is a very good teacher. During this year, most of his students got at least a C on the tests and there were many A's. On the last test, however, Mr. Jones got a big surprise. He wrote down all of his students' scores. Then he counted the number of students that got between 91 and 100. There were only two! Only two students got A's! He found out that there were only a few B's and C's. Most of the students in his class got a D or and F on the final test. Mr. Jones looked at the test again. He thought that it was too hard. He decided to give every student 10 more points. Then many of the students got good grades on the test. What a nice teacher!
