The best way to explore _______ countryside is on _______foot.
They ______ on the program for almost one week before I joined them, and now we ____ on it as no good results have come out so far.
---What’s that terrible noise? ---The neighbors ____for a party.
--- Hi ,Tracy, you look tired.--- I am tired. I ____the living room all day.
---- Isn’t it hard to drive downtown to work? ---- Yes, that’s why I ____ to work by train.
---Why you are so worried? --- I ___for my little son all the afternoon, I don’t know why he hasn’t come back so late.