and undoubtedly you have heard and used "who" questions many times before.

毫无疑问，你肯定已经听过并且使用过“who”问句很多回了。

Who 课堂 - SpeakingMax英语口语达人

And, you've undoubtedly heard a lot in the public press, and even in the political dialogue such as it is these days that hydrogen might be on environmentally friendly fuel.

毫无疑问你已经在公开新闻上，甚至在政治的对话上听到过了,比如最近这些天,氢气是一种环境友好的燃料。

麻省理工公开课 - 固态化学导论课程节选

If you go to Denmark and you break a $100 bill, you're going to be given one of these, undoubtedly, the 500 kroner note, which is worth about $75-80, and it has Niels Bohr on it.

如果你去了丹麦，换了100美元，毫无疑问，你会得到其中一个像这样的，500挪威币，约为75-80美元，上面有波尔的头像。

麻省理工公开课 - 固态化学导论课程节选

Now, you don't have to buy that and individuals undoubtedly found the strain too much from time to time, but what's interesting, is rather the ideal, the claim, the theory.

你不必非得接受这些理论,况且现代社会常充斥着个人主义倾向,但是那些理想,主张和理论却更意味深长

耶鲁公开课 - 古希腊历史简介课程节选

A very simple pattern that you undoubtedly have heard and used many times before.

这是一个非常简单的句型，毫无疑问，你肯定已经听过或使用过很多回了。

Where 课堂 - SpeakingMax英语口语达人

You've undoubtedly heard it many times before.

相信你之前已经听过很多次了。

When 课堂 - SpeakingMax英语口语达人

You're undoubtedly using it already.

相信你之前就已经用过了。

I didn't 课堂 - SpeakingMax英语口语达人

Let's is undoubtedly something you've heard many times.

不用说，你肯定听到过不少“Let's”的句子了。

Let's 课堂 - SpeakingMax英语口语达人