Billy: I’ve been fixing the computer for over three hours, but it still doesn’t work. Nana: Why don’t you take a rest and try 　　　?  Maybe you’ll do better then.

____ do you exercise ?

He has        work to do, so he can’t go with you.

 --____ has your grandpa lived here?       --Since last year.

Be careful!. We must _____ play on the street.