I once believed that a friend is a friend all the way. Now I have changed my ideas about friendships.

    1). Friends of convenience(便利). They can be the people who live next door or the mothers of our children's closest friends. Friends of convenience are good indeed. They'll help us when we need it. They'll look after our cats when we go on holidays. But we don't ever get too close or tell too much. Between us, we'll talk about being overweight but not about being sad or disappointed(失望). However, people still find it necessary to make friends like this.

    2). Special-interest friends. These friendships aren't deeply personal or emotional(感情上的). They lie in some shared interests, so we may have an office friend, a tennis friend, or even a shopping friend.

    3). Historical friends. We all have a friend who knew us when…maybe we were back in the second grade of primary school, when our family lived in that two-room flat downtown. He or she was the first, the only friend we told our secrets to.

    The years have gone by, and we have gone different ways. But we're still a personal part of each other's past. We know how we looked before our teeth were straightened(矫正), and our getting together makes us think of an earlier part of ourselves, which is important and never lost.

    4). Cross-generational friends. These are friendships that from across generations(代). I have in my own life a precious(珍贵的) friend, a woman of 65, who is clever, who listens well, and who means not only an ideal mother to me but also the person I'd like to be when I grow up.

    Best friends, I believe, totally love and help each other.