It shows an assessment of reading proficiency levels in fourth grade.

这项研究对,四年级同学的阅读熟练程度。

麻省理工公开课 - 媒体、教育、市场课程节选

So, if we want to figure out the formal charge on the carbon, we need to take the number of valence electrons, so that's 4. We need to subtract the lone pair, what number is that? It's 2.

如果我们想算出碳原子的形式电荷，我们需要将价电子的个数，也就是四，减去孤对电子的个数，它是多少？是二。

麻省理工公开课 - 化学原理课程节选

These studies were done in France with four-day-old babies.

这些实验在法国对四天大的婴儿进了研究

耶鲁公开课 - 心理学导论课程节选

And runners proved the doctors and scientists-- proved that they were right and ran the mile in two seconds and 4 minutes, one second, but no runner could run the mile in under 4 minutes, ever since the mile was actually timed-- when they started to time runs.

跑手们证明了医生和科学家…,证明了他们是对的,一英里跑四分钟两秒，四分钟一秒，但没有跑手能少于四分钟，从一英里跑计时以来-,当人们开始计时跑时。

哈佛公开课 - 幸福课课程节选