Some one must have slipped it slyly into my pocket for a joke.

一定是有人捉弄我，偷偷地把它塞进了我的口袋。

youdao

To go in for technical innovation, one must have the fearless spirit of a pathbreaker.

搞技术革新就要有一股不怕困难的闯劲。

《新英汉大辞典》

One must have a correct estimate of oneself.

一个人必须对自己有正确的估计。

youdao

They must have attended their American school for at least one year.

VOA: special.2009.01.29

A famous mathematician once said "Every question must have a correct answer " for every question one answer."

一位著名的数学家曾说过,“每一个问题都必定有一个正确的答案,每一个人们所回答的问题“

耶鲁公开课 - 政治哲学导论课程节选

And one thing that Einstein put forth is he figured if well, what we're saying is that light is, in fact, a stream of particles, each one of those particles or photons must, therefore, have a momentum.

爱因斯坦提出了一件事情,他指出如果我们所说的光，事实上是一束粒子，那么这些粒子或者光子中的，每一个都有动量。

麻省理工公开课 - 化学原理课程节选

To win, one must have a clear idea of what it fully takes to succeed and where that requires one to go.

FORBES: The Key to Becoming a Ninja Innovator

You said in one of your quotes that the first gold medal is always the most special, but this one must have been almost as special, at least as the first one?

BBC: News Online

One must have a place of refuge.

NEWYORKER: The Rebellion Within