按要求改写句子:(1)Waterisveryimportant.(改为感叹句)(2)I'dlikeapieceofpizza.(改为一般疑问句)(3)Aricedumplingcost(3yuan5jiao).(对括号部分提问)(4)I'mselling(American)food.(对括号部分提问)(5)HehasnevervisitedCanada.(改为反意疑问句)