词类转换 根据所给词汇，填入一个正确的形式。

1. Edison kept _______ out his new idea.(try)

2. Do you think the computer today is _______ inventions?(useful)

3. I saw a boy ________ on the railway tracks near the station.(play)

4. I want to learn how to run quickly and to eat _______.(health)

5. She speaks too quietly.Tell her ______ a little louder.(speak)