There are problem in that a horse must be treated when we study rigid bodies.

当我们学习刚体的时候,把马看做什么就是个问题了

耶鲁公开课 - 基础物理课程节选

And that makes it for me a very exciting time to study this because the problems aren't solved in the way that bridge building is largely a solved problem now.

对于我而言,这是一个非常激动人心的时代,因为一百年前桥梁建设中难以解决的问题,在今天都得到了解决

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What's true problem of that study?

这项研究到底揭示了什么问题？

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