Every time I came home from work at midnight, I often saw a shadow   walking in our neighborhood. Was it "a night walking"? Someone walked alone in the dark, and this always made me afraid a lot. I think it was "a sleep walker". So I never bothered it. But one night, when I walked past it quietly and quickly as usual, I heard a low voice. "Do you often have to work at night?" I was a little afraid. I looked around, but no one was nearby. I ran home as quickly as possible. Later on, I heard it was a neighbor, an old man who has been living alone at home. He's NOT a sleep walker. He enjoys having a walk at night. So I seldom see him in the neighborhood in the day. It's said that he was a soldier many years ago. He has two children, a son and a daughter. His son has a family in Shanghai. His daughter went abroad, in Sydney. He has been living alone since his wife died several years ago. Without any children living with him, he feels lonely and helpless. I feel sorry for the old man. We might care less about our parent who lives alone. When we grow up, our parents get old. We should often go back home even though we're busy with work. The writer mainly wants to tell us   _  .
We shouldn't work at night for money. Life is full of the unexpected. We should often go back home to see our parents It's best to live with your parents.