For instance in the past, we had that silly little program for computing the average of some quizzes and it was actually a pretty bad implementation because I had essentially hard coded in the number of quizzes.

比如在以前，我们做了一个,计算平均数的程序,这是一个相当挫的实现,因为我硬编码了测试的数字。

哈佛公开课 - 计算机科学课程节选

Numbers are hard. That's why we teach whole semesters worth of courses in number theory.

因此我们整个学期关于数学理论,的学习也是物有所值。

麻省理工公开课 - 计算机科学及编程导论课程节选

It's actually not impossible, but hard, and there are a number of challenges.

事实上，它并非不可能，只是很艰难，要面对很多挑战。

耶鲁公开课 - 金融市场课程节选

It's a secret number so that if Julius Caesar scrambled his message with the key 13, well, then the recipient had better know what that number is or realistically, -- and this is why it's kind of hard to buy -- into some of these age old algorithms, -- what would an alternative approach be to figuring out Julius Caesar's messages to his generals if he didn't know that secret number was 13?

它是一个机密的数字，以至于,如果凯撒大帝使用密钥13加密了它的消息，然后接收者最好知道那个数字是什么,实际上--这就是为什么很难,破解这些古老的算法-,有什么变换方法使凯撒大帝的将军,可以解密凯撒大帝的消息，如果他不知道,那个机密数字是13呢？

哈佛公开课 - 计算机科学课程节选

Problem is here, that Player II has a continuum of strategies and trying to draw all possible probabilities over an infinite number of objects on the board is more than my drawing can do. Too hard.

现在问题是,参与人II的策略是连续的,想要把无限可能性的概率,做成图都画在黑板上,是不可能的了

耶鲁公开课 - 博弈论课程节选