本次受到影响的关键系统是Fours quare的用户登入数据库。

The critical system that was affected was Foursquare's database of user check-ins.

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如果疑点很多，系统可能会要求再输入一条信息，例如从公共信息数据库中撷取的一条个人信息，然后才会允许这名用户完成登入。

If there's too much doubt, the system might ask for another piece of information, such as a personal detail pulled from public-records databases, before letting the user finish logging in.

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