want在什么时候不用加TO直接加代词名词动词

想要某物直接加名词，如I want a cup of water.
想做谋事加to再加动词原形，如I want to drink a cup of water.
想要某人做谋事用want sb to do sth，如I want you to give me a cup of water.

want 加名词和代词时本来就不用加to, 例如：I want it. I want you. I want mum. I want milk. want 接动词时才加to, 例如： I want to sleep. I want to eat an apple. I want to go out.want 可以直接加动名词， 例如：I want sleeping. I want crying. I want dancing. want 还可以这样用: I want you to go out! I want it to stay here.理解吗？