4.is playing　表达动作正在发生，要用现在进行时。主语是Tom,所以要用单数。　

3.don’t　表示现在时刻的状态、能力、性格、个性，应用一般现在时。　

2.moves　本句为客观真理，应用一般现在时。　

10.-Can I join your club,dad?　

-You can when you _______ (get) a bit older.　

答案：1.is　本句为一般现在时，而且主语是第三人称单数。　

9.The train _______ (start) at two.　

8.Light _______ (travel) more quickly than sound.　

7.America is growing older today,10 out of every 100 Americans _______ (be) over 65.　

6.You _______ (work) from 9:00 am to 4:30 pm every day.　

5.Failure _______ (be) the mother of success.　

4.Tom _______ (play) basketball now.