So they're optional, but they're very, very, very highly encouraged that you do these, because this is going to give you practice for the types of problems that are going to be on the exam.

虽然它们是选做的，但是它们非常非常，非常值得你们去做，因为这对你们来说是一次训练,是用来熟悉考试题型的。

麻省理工公开课 - 化学原理课程节选

And then other people are really excited because it's a once-in-a-lifetime opportunity

而另外一些人真的很兴奋，因为这是一个一生只有一次的机会，

正准备奥运会 - SpeakingMax英语口语达人

You have to be comfy on camera but this is your first chance to say hello to mom and dad on camera.

在镜头前表现得自然点儿,因为这是你第一次在电视上跟爸妈打招呼。

哈佛公开课 - 计算机科学课程节选

Because here he was for the first time in-- well, since my wife and I were together-- someone else is getting much more attention than I was, no matter how much I cried.

因为这是妻子和我在一起后-,第一次有人夹在中间-,另一个人比我获得更多的关注，不管我怎么哭。

哈佛公开课 - 幸福课课程节选

It's a fantasy, of course, because no such brainwashing is going to be possible, just as the fallen angels - if you look at line 607 - will be barred from drinking their fill of the river Lethe, forgetfulness is impossible.

当然这是一次幻想，因为这种洗脑,根本就不可能实现，就如同那些堕落天使一般,如果看第607行7,他们被禁止喝忘川之水，遗忘是不可能的。

耶鲁公开课 - 弥尔顿课程节选

Because for the first time, you're being taught by people who are smart as you are.

因为这是第一次，教你们的人和你们一样聪明。

麻省理工公开课 - 固态化学导论课程节选

Once again, it's about chipping away the excess stone because as kids, we are always asking questions.

再一次，这是关于凿掉多余的石头，因为作为孩子，我们永远都在问问题。

哈佛公开课 - 幸福课课程节选