Play appears to be a developmental characteristic of animals with fairly sophisticated nervous systems, mainly birds and mammals.

玩耍似乎是具有相当复杂的神经系统的动物（主要是鸟类和哺乳动物）的一种发育特征。

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Due to the key role that those services play, they often span multiple backend systems.

由于这些服务扮演着关键的角色，因此经常会涉及多个后端系统。

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Many other common free-to-play perk systems are also represented in Arcane Legends, such as a daily login bonus.

FORBES: Arcane Legends: A Hack And Slash Home Run

We all play different systems with our clubs and everybody knew their roles and had worked hard on it all week.

BBC: Scotland boss Craig Levein defends system in defeat

It caused both companies to delay their next systems, and play catch-up by creating motion systems for their own consoles.

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