For most men and women, fitting in an hour of moderately intense exercise in an already hectic day is difficult, if not impossible.

VOA: standard.2010.03.30

Some people in this room might be hubs, and it is not impossible to find out.

这个教室里可能就人这样的人，要找出来很简单。

耶鲁公开课 - 心理学导论课程节选

but he's also insisting that this is an incredibly difficult, if not impossible, moment of thought.

但他同时坚持，如果可能，这对思维来说也是一个极其艰难的时刻。

耶鲁公开课 - 文学理论导论课程节选

(SAYING) Mely says that while the push for immigration reform is difficult, it should not be impossible.

VOA: standard.2010.03.21

But not seeing how it's possible is not the same thing as seeing that it's impossible.

但现阶段无法预见其可能,并不代表永远不可能

耶鲁公开课 - 死亡课程节选

If it's not clear, the problem is going to be impossible to solve.

问题也就不可能，得到解决。

麻省理工公开课 - 热力学与动力学课程节选

For if I say that this is to disobey the god and because of this it is impossible to keep quiet, you will not be persuaded by me on the grounds that I am being ironic.

因为假设我说那是违悖神意,所以我无法保静默，你们不会被我说服,反而会以为我语带讽刺；

耶鲁公开课 - 政治哲学导论课程节选