首先，结识不同种类的朋友最明显的好处是：你可以享受很多的乐趣。
Firstly, the most obvious and undisputed advantage of having a different friend is that you can enjoy morekinds of amusement.
在美国，同伴一起玩，但并不是做什么都在一起，这一现象并不很少见。不同种类的朋友参加不同的活动。
It's not uncommon in the U.S. for friends to enjoy each other's company but not do everything together; often different friends enjoy different activities.
世界上现存成千上万的不同种类的动物，人类已经学会了同其中的许多动物交上了朋友。
Of the thousands of different kinds of animals that exist in the world, man has learned to make friends with many of them.
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