一.用所给词的适当形式填空
1.David has ___________ (win) several science competitions.
2.He is not afraid of making a ________________ (speak) in front of many people.
3.He has learnt to use the computer to get himself ______________________ (organize).
4.David spends lots of time _________________ (help) with others after class.
5.He thinks he can do anything if he ___________ (try) his best.
6.We think David is ______________________(suitable) person to be our monitor.