---Whose purse is it? ---If it isn’t yours, it must be _________.
My brother is an active boy, he often risks _____ mountain with his friends.
—What’s wrong with my son? —______Serious, it’s only a cold.
I can’t go to bed because I still have _____ homework to do.
Simon, you’d better ______ enough water, it’s hot today.
—Hello! Is Wang Tao in? —________.