Like most such online worlds, WoW is also a pay-to-play world-a credit card is mandatory for each player.
和众多的网游类似，魔兽世界也是一个付费游戏，玩家必须持有一个信用卡。
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Students use forums to chat, play games, and solve problems together at no cost, or they can pay a few hundred dollars to take courses with trained teachers.
They are open to the tactical possibilities and the musical challenges precisely because they are freed, through skill, from the need topay attention to the low-level details of how to play.