英语.用must,must't回答You()drawontheblackboard.You()returnthebooksintime.
You()steponthegrass.
You()putthebooksbackafteryouhavereadthem.
You()talktothedriverwhentheschoolbusismoving.
You()cleantheclassroomeveryday.
You()waitinlinefortheschoolbus.
You()talktooloudlyinthereadingroom.