At the beginning,time is the main element to account for this.The longer you know a guy,the much degree you will know this guy.There no deny that we can’t know much about a guy if we just recognize him/her for a peroid of time.on the contrary,it is universally acknowledged that we have known our friends for a long time.A good case in this point is myself:,It is in my first semester.i made friends with my roommate,who i thought he was honest.however,he told lie to my other roommate,and he even cheated in the exam.Time is important,but it is only just one of the aspects. It is no dount that intention makes some influence.Why should the guy make friends with you?Just only he/she want to make friends you,or the guy wants something behind you?The answear we don’t know.If the guy make relationships whith you just for money or something else,on the other hand,you try your best to treat the guy.It is not until the time that the guy broken you heart you will relaize so precious the old friend is. Maybe someone would ask”if i don’t make friend with the guy,i wouldn’t know if the guy is a good one? perhaps this (is)correct,but I think another aspect will state this clearly:relationship.Relationship means the contaction between you and the person around you.As time goes by,we can know more and more people.But,the one really wants to hear your words in your heart will never show up.They do things for their own benefit.nobody cares about you if you are happiness or sadness today.A good example for this is :when you feel unhappy who is the first person you will think,the old friend or the new friend?The answear is clear:Old friends will hear your complaint and do their utmost to make you happy.By making you calm down ,they bring you back to the earth.Making new friend also has some benefit.For example,you will learn something from your new friend,and you may get something you need from your friend.However,obviously,the benefits of keep relationship with old friend exceeds the advantage of making a new friend.To sum up,we cannot emphasize the importance of keeping relationship with old friends.