In 1988, psychologist Fritz Stack asked a group of participants to clench a pencil between their teeth for 20 seconds so that their lips did not touch it, creating the impression of a smile.

1988年，心理学家Fritz Stack让一组参与者用牙咬住一支铅笔20秒，以便不被嘴唇碰到，这样就有了一个微笑的表情。

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By dropping tabs on top of one another in Opera's new beta version, you can create a "stack" -a single unit on the TAB bar that contains a group of open pages.

在Opera新的be ta版中，可以将一标签撂到另外一个标签上，就形成了一个“栈”——标签栏上的一个单独单元，包含一组打开的页面。

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It's a group of related activities, arranged in a stack.

任务就是以栈的形式组织起来起来的相互关联的一组活动。

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Stinebrickner-Kauffman says a representative from her group hopes to deliver a stack of petitions to Apple executives during the meeting tomorrow.

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Zylstra and a group of seven studied the problem, then resolved to stack those parts 50 feet away in the machine shop area.

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