The Olympic Rings _________ the five parts of the world.
______ does this scarf belong to? — Let me see. Oh, it may be ______.
The Math problem is too difficult , we really don’t know ________ to do it .
David, how old is your father this year? – ———— And we just had a special party for his _____ birthday last weekend.
Why do you appreciate her help so greatly?一Because her donation makes it possible for methe dog Lucky.