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.
— Are you a teacher? — No, but I ____. I worked in a middle school for three years.
— How are you getting on with your work? — Oh, I’m sorry. Things aren’t going so well as ____.
— Why do you want the book so much? — ____, sir.
— I hate talking with that guy. Look, he is coming. What should I do? — Don’t speak until ____.
I hear Mr. Smith was writing a story last year and he still ____.