根据短文内容及首字母提示完成短文。（每空一词）
   Friends play an important part in our lives. We may have many friends, but we often don't understand c____how we make friends. We may get on well with a n____of people, but we usually make friends with a very few of them.
   People use the word "friend" freely. Friends may k____each other since childhood or they may recently meet. In fact, people many have different k____of friends such as school friends, work friends, or sports friends. A person may c____different friends for different activities. If you play with s____  on the playground, the person is your playmate. If you often play chess w____ a friend, the person is your chess partner.
   One may have many good friends and only one best friend. " Best friends" or "close friends" are u____two people who have known each other for a long time. A close friend is someone who is able to s____ experience, joys and sorrows(悲伤) with you. This is a person you can rely on (信赖) when you are in n____, and this is the person to whom you are willing to lend a helping hand.
   Friendship is one of life’s greatest treasure.