It's the difference between a pass and a fail.

这是及格和不及格的区别。

《柯林斯英汉双解大词典》

There are certain tests that fail at times and pass at most other times.

某些测试有时候会失败，但是在大多数时候会顺利通过。

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Since these are expected occurrences, the daily pass/fail graphing (although popular) isn't a useful indication of the actual health of the product.

由于这些是预期的事故，所以每日的通过/失败图表（尽管很流行）不是实际的产品健康的有用的指示。

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In fact one of the frankly best things I ever did as an undergraduate was, perhaps fittingly, take this course pass-fail.

实际上我上本科时做的最得意的事,恰当地说，就是把这门课的成绩看成及格和不及格两种。

哈佛公开课 - 计算机科学课程节选

So you may take this course ultimately via pass-fail or letter grade and I am more than happy to chat with you about the implications and to sign any paper work such as the stack here that you might need.

你可能希望这门课采用及格-不及格分制或者分数制,我很乐意跟你聊下,两个打分制各自的含义,也可以帮你在这里签到。

哈佛公开课 - 计算机科学课程节选

And this is absolutely not true; it's for the most part the entire freshman year for instance at MIT is taking pass-fail.

这绝对是不正确的;,例如，麻省理工学院的大部分新生在第一年参加的课程,都是采用及格-不及格的打分制度。

哈佛公开课 - 计算机科学课程节选

New sunscreen labels in effect this year require a pass-fail test for UVA and UVB protection.

WSJ: European Sunscreen Roadblock on U.S. Beaches

And we shouldn't expect some binary moment, a pass-fail grade where, you know, the whole war, yes or no, is decided.

NPR: President Bush Airs His Ideas About Iraq and Iran

As the ultimate pragmatist, he'd no doubt go for the pass-fail option.

CNN: ASIANOW - TIME Asia | Asia Buzz: A Scorecard for China