There are more than 20 amino acids that make up the biological polymers called proteins, so there are 20 choices of each amino acid at a position on a protein.

而那些称为蛋白质的生物活性多聚体,是由二十种不同氨基酸所构成,因此每个蛋白质的,任意位点都有多达二十种氨基酸可供选择

耶鲁公开课 - 生物医学工程探索课程节选

I already owed 20 dollars and haven't been able to talk for more FML than five minutes without getting called out on it FML.

我得付二十美元，还没说上五分钟,还没有谈到。

哈佛公开课 - 计算机科学课程节选

So, the dollar group rated a task as more fun than the twenty dollar group.

比起20美元那组，一美元认为任务更好玩。

耶鲁公开课 - 心理学导论课程节选

That creates a problem in the genetic code in that there's 64 possible sequences but there's only 20 some amino acids, so each amino acid can be specified by more than one codon.

这里有个问题,遗传密码有六十四种可能的序列,而只有二十种氨基酸,因此每种氨基酸都有,不止一种密码子与之对应

耶鲁公开课 - 生物医学工程探索课程节选

More than just a little. -More than just a little 20% Federal spending is now about 20 percent of GDP ? three years from now, higher, lower or about the same?

不只低一点，-好吧,目前，联邦财政支出占GDP的,3年后，这个比例会升高，降低，还是持平？

斯坦福公开课 - 经济学课程节选

It's not meant to be more than five, ten minutes of work, but the point of the question, -15, 20 minutes of work, but the point of the question is to motivate people to keep up with the material and do the readings.

几分钟就能完成,这个作业的目的,要十几到二十分钟完成吧,这个作业的目的在于激励大家,跟上课程的进度并去阅读材料

耶鲁公开课 - 心理学导论课程节选