100. Taking this medicine, if ________, will of course do good to his health.
--- I’m afraid I can’t return the book to you before Friday. ---_______.
They are so busy that they have no time to do any sports, ______they need to do so.
I don't know _______.
Hurry up! The train ______. You know it ______ at 8:30 am.
The head teacher insisted that every minute ______ made full use of ______ for the mid-exam.