根据句意，用括号内所给单词的适当形式填空

1. I saw the ______(happy) from his face and tried to cheer him up in my own way.

2. We'd better eat as ______(health) as we can and not go to bed too late.

3. Some animals are ______(active) during the daytime, but they are active during the night.

4. My mother has got a bad toothache so she has to go to the ______(dentist).

5. He had a party to celebrate his father's ______(forty) birthday.