Many people don't understand how much water the human body n

Many people don't understand how much water the human body nees and many people don't drink enough
water.这句的句子结构是不是：many people主语,don't understand 谓语,how much water the human body nees 同位语还是宾语（怎样判断）,and many people don't drink enough water.并列句（many people 主语,don't drink 谓语,enough water宾语）,