六十位年龄在二十五到五十岁之间的身体健康的男性在六周之内，每天都食用了这种草本植物的提取物。

Sixty healthy men aged between 25 and 52 took an extract of the herb twice a day for six weeks.

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第二步，再花三十年到五十年时间，接近发达国家的水平。

The second goal was, within 30 or 50 more years, to approach the level of the developed countries.

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我们学校的历史可追溯到五十年前。

The history of our school goes back to fifty years ago.

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They also found some stockpiles of the virus from the 1950s that they still had on an Army base in Maryland,I think.

政府也在马里兰军队驻地发现了,从十九世纪五十年代储存到现在的病毒

耶鲁公开课 - 生物医学工程探索课程节选

I would guess that probably 30% to 50% of you do this everyday, you put a piece of plastic, a synthetic piece of plastic into your eye to improve your vision.

我猜你们有百分之三十到百分之五十的人,每天会做这样的事,将一小片塑料,合成塑料放到眼睛里,来提高自己的视力

耶鲁公开课 - 生物医学工程探索课程节选

You can find a whole- you can sort of find a deep and abiding kind of American nationalism still in a lot of these budding Southern patriots, even by the 1850s, especially when they get scared about what secession might actually mean.

你会发现,可以说你会发现一种深层持久的,美国民族主义仍旧根植于许多,南方爱国者们心中,甚至到十九世纪五十年代还是如此,特别是当他们开始害怕,脱离联邦会导致何种不可预料的结果

耶鲁公开课 - 美国内战与重建课程节选