Some of them have some of the coupons clipped and then they stop and you know that it was bad news when they stopped clipping them.

一些息票被剪下来并兑现了,而随即又停止,当他们停止剪票,这可是坏消息

耶鲁公开课 - 金融市场课程节选

The lever gets them out of the box, but after more and more trials they stopped scratching at the bars, pushing at the ceiling and so on.

杠杆让它们逃出迷笼，但在经历多次尝试之后,它们不再抓栏杆，不再推顶棚。

耶鲁公开课 - 心理学导论课程节选