The idea of negative CAPTCHAs is not to ask a user to proof that he is human, but reveal that a spam robot is a bot.

这个消极的CAPTCHA的主意，不是去让用户证明他是一个人，而是让一个机器人证明他是个机器人。

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You can stop a great deal of spam by detecting typical robot workflow, which goes straight to the POST request.

机器人工作流一般径直进入 POST 请求，因此通过检测典型的机器人工作流可以禁止大量的垃圾信息。

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Spam and robot-generated tweets were eliminated, he said, as well as off-topic tweets.

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