We're still close enough to the summer that the air is not just filling us up with extra static electricity, so it's a little more challenging here.

我们现在离夏天更近了,这样空气中不总是,充满额外的静电，所以这时做实验,会有一些挑战性。

麻省理工公开课 - 化学原理课程节选

And I'd like to leave you with a challenging question.

下面我想留给你们,一个具有挑战性的问题。

麻省理工公开课 - 媒体、教育、市场课程节选

We differ from lower animals and our brains, which are much more capable of storing and processing information, but we're living in a time of revolution when machines are challenging or competing with our brains.

我们不同于其他低等动物，我们的大脑更能够存储和处理信息，不过身处改革年代,机器开始挑战甚至是,和我们的大脑开始竞争。

耶鲁公开课 - 金融市场课程节选