Friends from whom we could get knowledge and happiness are important persons who we cannot live without,but what personalities do we think our friend must have?Some people may think of intelligence.some might say humor.but as far as I'm concerned. reliability is the most important thing.I have to say that intelligence and humor are also vital spirits which a friend should have.but comparing with reliability they could be ignored. Reliability is a symbol of a kind of people who is worth to be trusted.which also means that when we need help,we needn't worry about whether he or she can give us a hand.It is the same as that when a man is walking in the rain,he will never be afraid that the rain is too heavy to carry,because he is so sure about the rain.A reliable friend is just like the rain in the story who we are sure about that he or she won't do any harm to us.And the other two points are less important than reliability. I think that an intelligent friend who is not reliable might be a dangerous person who l rather get far away from,because I never know when he or she will betray me. All the contents above are the reasons why I argue that reliability is the most important personality of a friend.