This material will be necessary to do the listening exercises for the course, which is sort of the backbone of the course.

做听力练习时我们必须使用这些材料,听力训练是课程的核心内容

耶鲁公开课 - 聆听音乐课程节选

Do you think an undergraduate degree should be necessary to enter law school?

你认为进入法学院前必须要有本科学位吗？

想成为律师的话 - SpeakingMax英语口语达人

It's not necessary to do that, but it can be quite convenient.

虽然没有必要这样做，但是这样做是很方便的。

麻省理工公开课 - 热力学与动力学课程节选

As completely as was possible and is necessary, would you choose to do it?

如果完全可能而且必要，你会这样做吗？

麻省理工公开课 - 媒体、教育、市场课程节选

Yes, I do believe it's theft but perhaps it is necessary to condone that theft.

我确实认为这是盗窃,但也许我们有必要容忍它。

耶鲁公开课 - 公正课程节选