Well, I talked about the problem of using plasmids in gene therapy, that it's very difficult to get them into cells.

我们之前讨论过,基因治疗中运用质粒的问题,质粒本身极难进入细胞

耶鲁公开课 - 生物医学工程探索课程节选

That's a tough question.

这问题比较难回答。

艺术画廊，来吧 - SpeakingMax英语口语达人

These are the questions that are asked by what's called hermeneutics, a difficult word that we will be taking up next week.

这些是所谓诠释学提出的问题，诠释学是个难词，我们下周再讨论。

耶鲁公开课 - 文学理论导论课程节选

So that's really - these are really difficult questions to answer.

所以这些问题,这些问题都是极难处理的

耶鲁公开课 - 生物医学工程探索课程节选

That's not hard; you have it right in front of you.

并不难回答的问题，可以从你面前的那张纸上找到答案。

耶鲁公开课 - 旧约导论课程节选

That was a really hard question.

刚才那个问题挺难的

耶鲁公开课 - 聆听音乐课程节选