He called Iran "one of the most complex national security problems" the United States has faced in his more than 40 years in government.

VOA: standard.2009.12.12

So that you will come away with a sense of what you can do, what you can't do, and what kinds of things you should use to tackle complex problems.

因此你们才能对,你们能做的事儿，不能做的事儿,和用何方法去,解决棘手问题有一个基本概念。

麻省理工公开课 - 计算机科学及编程导论课程节选

That's really a complex systems problem, the kind of problems that engineers are very good at dealing with.

这真是复杂的系统性问题,解决这类问题,恰恰是生物医学工程的拿手好戏

耶鲁公开课 - 生物医学工程探索课程节选

The problems are complex because we're trying to make a system in which people are able to make their own decisions as much as possible and to make them in a way that--in an environment that they trust.

问题总是复杂的,我们试图创造一个,人人都可在其中,尽情决策的系统,创建一个,人人彼此信任的环境

耶鲁公开课 - 金融市场课程节选

I think that book will give you all the basic principles you need in calculus of one variable, more variables, elementary complex numbers, maybe solving some problems with vectors and so on, which you're going to get into.

我想那本书会给你所需的所有基本知识,包括一元和多元微积分,简单的复数运算,可以解决一些与矢量有关的问题,而这正是你们将要学的

耶鲁公开课 - 基础物理课程节选