Airdrop a placeable Sentry Gun.

空投一具可放置的步哨机枪。

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If you're in an open place, look around after selecting the Sentry Gun and you will see a grid appear which indicates the line where enemies cross to trigger the auto-aim feature of the Sentry Gun.

当你在空旷区域放置步哨时，仔细观察四周你将会看到一层网格，表示步哨将会自动攻击此范围中的敌人。

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The Marines can get hold of a sentry gun, though none of the matches I saw or participated in managed to do so.

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