---Why did _____ take Aunt Alice almost an hour to get home ? ---I don’t know . Maybe there was something wrong with her car . 

There is ___ food in the fridge(冰箱). Let’s buy some.

David talked with a friend of ________ on the Internet for a long time yesterday.

--- Are these your bikes?---No, _______ aren’t.

Tom has to leave now _________ he can catch the train.