一、单选。( )1. As a student , you must be careful _your homework.A. of B. to C. with ( )2. Children should talk their parents.A. to B. of C. about ( )3. Look! So many people are getting _ the bus. A. up B. on C. of ( )4. Can I use _ book? isnt here.A.your; mine B. your; my C. you; mine ( ) 5. At the moment, my littl