如图所示，用塑料尺用力击打一摞棋子中的一个，该棋子飞出而上面的棋子又落到它原来的位置，是由于它们具有____ ．棋子飞出的瞬间运动状态是发生改变的原因是塑料尺施加的____ 的作用．下面两个棋子静止不动，是受____ 力作用．

    My name is Jim. I am a student. At school, I have a good friend. His name is Mike. He is tall. He has short hair. We are classmates, too. We go to school at  7:00  o'clock. We go home at  5:00. It's  3:15  now. It's time to play games. Let's go to the playground. We play football with some boys.

They are         too.

①N₂+O₂ $\frac{\underset{\_}{放电}}{}$ 2NO        

②4AgNO₃ $\frac{\underset{\_}{△}}{}$ 2Ag₂O+4NO₂↑+O₂↑

③2NH₄Cl+Ba（OH）₂ $\frac{\underset{\_}{△}}{}$ BaCl₂+2NH₃↑+2H₂O．