根据句意，选用方框内所给词的适当形式填空。

east  sixty  health  know  discuss

1. After a ____________, both sides reached a final agreement.
2. Japan is to the ____________ part of China.
3. To live ____________, you should change your lifestyle and diets.
4. Scientists are always trying to discover the ___________ world to human beings.
5. Audrey Hepburn, who died in her __________, devoted all her life to charity.