When did you ___________ the army?

I found there was only one copy of “Bighead Son and Small-head Father” on the bookshelf, so I decided to buy _______ at once.

Tom was about to close the window ___ his attention was caught by a bird.

Is this your baseball?—No, it’s Bob’s. Baseball is _________ favorite.

What were you doing at this time yesterday? —I ______ on the grass and playing with Tony.