The first one is 'medicine';
Simply like medicine, it helps you. It relieves you. But you can't have too much of it. Overdosage can bring you a lot of harm.
The second one is 'Poison';
No matter how hard you try it will always bring harm to you. This is a type of friend that you should avoid.
The third one is rice;
Something you can't live without.
So cherish your friends and families. They are you backbone. Pillars that supports you.