But for people who have a difficult time controlling their movements, this little navigational issue can be a really big problem.

VOA: special.2011.04.18

The first study, the one with the deceptive dolls with the big shoes and little shoes, is actually fairly difficult.

第一个研究用了有欺骗性的,穿着大鞋和小鞋的洋娃娃,实际上是非常难的

耶鲁公开课 - 心理学导论课程节选

So I think that it's true that the economy is difficult and there is big challenge in front of us.

所以我觉得，目前的经济形势真的很困难，我们面临着很大的挑战。

事业就是挑战 - SpeakingMax英语口语达人

Tough talk from a man who has made life difficult for big Wall Street firms that survived the financial crisis.

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This dynamic is also making things comparatively more difficult to build big, utility-scale solar power projects.

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We have been trying to keep things in perspective, although that's been difficult as the big day approaches.

BBC: Big day out