You must change the water more often 改为祈使句

You must change the water more often 改为祈使句 改为祈使句you must water it twice a day You must clean the classroom.(改为祈使句) You must be more than 10 years old.(改为祈使句) You cant pour dirty water into the river改为祈使句 You must remember to drink more water.变祈使句怎么变 You must turn on the blender,first.改为祈使句 you must cut up the bananas(改为祈使句) 急,改为祈使句you must obey the school rules You must be careful when crossing the street.改为祈使句 You must close the windows at night.（改为祈使句） you must put these things into the blender改为祈使句.