By 1860 there were approximately 4,000,000 slaves in the United States, the second largest slave society slave population--in the world.

截至1860年,美国大约有,四百万的奴隶,也因此使之成为了,世界历史上的第二大奴隶社会

耶鲁公开课 - 美国内战与重建课程节选

there're 4 million people living in Brooklyn by itself.

在布鲁克林住着四百万人口。

在布鲁克林的生活 - SpeakingMax英语口语达人

As much as we know about tobacco in the United States and the fact that there are only half the number of people smoking than used to be the case, it's still expected to rise by 45% worldwide By 2030 the deaths attributed to smoking will increase from four to ten million.

就我所知美国的烟民情况,在美国吸烟的人数,只有过去的一半,在世界范围内仍有预计45%的增长,到2030年,死于吸烟的人数,将由四百万增长至一亿

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

If I had a beaker sitting on the table here and it contained a million blue double stranded DNA molecules and a million red double stranded DNA molecules and I heated it up and added a little base, I'd soon have four million individual strands just floating around in the solution because I've broken up this hydrogen bonding and the DNA molecules fall apart.

假如我这里有一个烧杯 里面,盛有一百万条蓝色DNA双链和,一百万条红色DNA双链,然后我稍微加热一下烧杯,并且加一些碱,很快我就有了四百万条DNA单链,漂浮在溶液里,因为我已经使得氢键断裂,DNA双链也随之打开

耶鲁公开课 - 生物医学工程探索课程节选