I.单项选择。（每小题1分，计15分）
( )1.These books are _____. _____ are in _____ bags.
A. my. You, You B. My, Yours, your C. mine, Your, Yours D. mine, Yours, your
( )2.Why not _____ your mother cook supper?
A. helping B. to help C. help D. helping
( )3.Let Tom _____ right away.
A. go home B. to go home C. goes home D. goes to home
