七年级后的那个夏天，学生们要在大学校园里待上三周，每天学习七个小时的高等数学。

The summer after 7th grade, students spend three weeks on a college campus studying advanced math for seven hours a day.

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他们会在牢房外呆上三到十个小时，期间他们锻炼、吃饭、学习、看电视并与其他囚犯聊天。

They spend three to ten hours outside their cells when they exercise, eat, study, watch TV and talk to other prisoners.

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如里我去黄山，我会在那儿呆上三天。

If I went to the Huangshan, I would stay there for about three days.

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so you can see that there is going to be two sets in antibonding, three sets in bonding for a net of one, giving us the single bond.

因此你能看到,反键轨道上有两组，三组成键，得到一组净成键，所以成的是单键。

麻省理工公开课 - 固态化学导论课程节选

They're derived from a precursor called triacylglyceride, which is as glycerol molecule with three fatty acid chains dangling off of it.

它们来源于一种叫三酰甘油的前体,由甘油分子上连接了,三个脂肪酸链构成

耶鲁公开课 - 生物医学工程探索课程节选

I've been here in MIT for thirty years, and in the early nineties I taught the large freshmen physics course, and electromagnetism.

我麻省理工工作三十年了，在上世纪九十年代初,我就开始给大一新生上物理课，以及电磁学。

麻省理工公开课 - 媒体、教育、市场课程节选