Most American colleges and universities use the grading system of A,B,C,D and F.

VOA: special.2009.03.05

This refers--this actually goes back to B.F. Skinner, a psychologist who flourished in the first half of this century.

这要追溯到B.F.斯金纳,一位活跃在上世纪前期的心理学家

耶鲁公开课 - 金融市场课程节选

int A Well, one, function has called swap, takes one int called A, printf followed by another int called B, and as we've seen with print F, if you have multiple arguments, you separate them by commas.

好的，函数叫做swap，一个参数是，另一个参数是int，B，我们看到的,如果你有好几个参数，把它们用逗号分开。

哈佛公开课 - 计算机科学课程节选

So they began to call this A and this B and this C and this D and this E, this F, this G.

他们开始把这叫做A,B和C,这个是D,E,F,G

耶鲁公开课 - 聆听音乐课程节选

A Review of B. F. Skinner Chomsky is one of the most prominent intellectuals alive.

s，Verbal，Behavior,乔姆斯基是如今仍然在世的,最杰出的学者之一。

耶鲁公开课 - 心理学导论课程节选