How long will you keep in touch with a stranger? I have much experience to help lost people, those are new to Shanghai and get lost in the directions. Some of them will want to be my friend, I feel it's cool to get new friends in this way. And one thing I feel that no matter how well we get along with each other, the friend relationship often goes to a cold way after almost a few months. So I just wonder that how long will people keep in touch with a strang? Is that true only those know from childhood could be in a stable state in the relationship?