学生平均每天要花三个小时来完成作业，但是如果遇到难题，完成作业的时间就得延长。

On average, students have to spend 3 hours finishing homework every day, but if we are stuck by difficult questions, the time will be extended.

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迟早都会遇到难题的。

Sooner or later, a problem will arise.

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一位读者给我来信，是关于她遇到难题的一位亲戚的。

A reader wrote to me about a difficult relative.

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And he modifies them or revises them or introduces new positions to deal with some of the difficulties that he was setting himself to be open to earlier.

他会调整,修改那些观点,或者以引入新观点,来解决先前他遇到的难题

耶鲁公开课 - 死亡课程节选

Yes, I have. Freshman year, I was having a lot of trouble in my Physics class, and

是的。大一那年，我在物理课上遇到了很多难题，

与教授的面谈 - SpeakingMax英语口语达人

We just sat down and like, worked through exams and problem sets together

我们就坐在一起讨论考试还有我遇到的难题，

与教授的面谈 - SpeakingMax英语口语达人