You could see, for example, when it's expressed in a cancer cell, and where it's expressed.

你可以看到，比如说，它什么时候在癌细胞里被表达，在哪里被表达。

麻省理工公开课 - 化学原理课程节选

You can say like, if you are trying to describe something, you can say like,

你可以这样说，当你想描述什么东西的时候，像这样，

紧张是学英语的敌人 - SpeakingMax英语口语达人

So you've got to understand when it's okay and when it's not okay.

你必须得知道,什么时候可以,什么时候不可以

耶鲁公开课 - 基础物理课程节选

So there'll be options about when your discussion section will meet.

你可以选择,什么时候与讨论小组会面。

耶鲁公开课 - 新约课程节选

Then later on,whenever you want, you can take your money out Meanwhile, they invest the deposits some way or another at a higher interest rate than they pay on the deposits and they make the difference and that's how they make a profit.

然后你什么时候需要你就可以把钱取出来,同时储蓄机构以比给你的利息,更高的利息储蓄,或者投资，这就出现了差价,这就是储蓄机构盈利的方法。

耶鲁公开课 - 金融市场课程节选

Use this pattern when you wish to express what you are doing right now.

当你想表达目前你正在做什么的时候，你就可以用这个句型。

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