根据句意及汉语提示用所给词的适当形式填空。
Get up and go to bed early are good _______ (习惯).
Michael thinks walking is a good way to relax _______(他自己).
He isn’t at school now. _______ (或许) he is at home.
It is doctors’ duty to _______ (拯救) the patients.
We should sleep _______ _______ (至少) 8 hours every day.