There are eight tips in Dr.Roger's lecture on sleep,and one of them is:________ to bed early unless you think it is necessary.
The boy always spent the whole day ______ in the room reading English during the holiday.
Bad habits, _______ formed, are difficult, and sometimes impossible to shake off.
The monument was built in honor of the explorer who was believed _____ the river.
________ blood if you can and many lives will be saved.
_______ the morning of my mother’s birthday, I usually help my mother do some housework.