根据句意用所给词的适当形式填空. 1. I don't know what made him laugh so _____ (excite)? 2. Andy Law will give two _____ (perform) in Nanjing this year. 3. He made a _____ (decide) not to go there this week. 4. Most international _____ (busy) letters are written in English. 5. 'We are proud of your _____ (successful), Daniel.' said father.