you must be careful when you ___ with fireworks

you must be careful when you ___ with fireworks when crossing street,you must be careful You must always be careful with it . you must be careful You must be careful with your handwriting.(改为祈使句）___ ___ wit you must be careful when you （ ）the street You must ___(be) careful (在红绿灯处） You must be careful when crossing the street.改为祈使句 改祁使句 you must be careful with your pronunciation You must be careful with your handwriting(改为祈使句) you must be careful with your pornunciation.改为祈使句 When you are dealing with these wastes,do be careful.