They say they do not think Iran will engage seriously in the absence of what would be a fourth round of sanctions by the U.N.Security Council.

VOA: standard.2010.05.14

Try to imagine-- can you do that or can you not do that?-- try to imagine a round square.

试着去想象,你可不可以这样,试着去想象一个圆的方形

耶鲁公开课 - 死亡课程节选

So the problem I want to do-- there are many things you could do but I just picked one, and this is the one with round numbers, so I can do it without a calculator.

我想讲的这道题,类似的题目很多,但我就选了其中一个,这道题涉及的数字都是整数,所以我不需要计算器

耶鲁公开课 - 基础物理课程节选