In any case, whatever one makes of those examples, Machiavelli seems to be challenging important aspects of the classical conceptions that we've been talking about up to this point.

不管人们如何理解这些例子，马基雅维利似乎正在挑战,我们至此一直在讨论着的古典概念的,重要方面。

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because school can be really challenging and stressful,

因为学校的学习很有挑战性也很有压力，

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I think this is as good list so let's go and think about what might be a little bit more challenging.

我想上面这些都是很好的例子,接下来我们思考一些更有挑战的问题

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We're going to really get into this next class, but I just want to introduce it to you to give us a start, and many of you have used Lewis structures in high school, but we'll be doing some much more challenging Lewis structures, I can assure you, in this class here.

其实我们下节课才会详细介绍它，但是今天我只想以简单介绍作为开始，大部分同学在高中就用过路易斯结构了，但是我们会遇到一些更具挑战性的,路易斯结构，我可以向大家保证，在这门课中会的。

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It can be very, very challenging.

这非常非常具有挑战性。

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