So that's where you have to think about whether it's positive or negative.

你就要想想，它是正还是负,你们现在不需要。

麻省理工公开课 - 化学原理课程节选

Now the bases, and you don't need to memorize the structures of these I'm going - I'm describing the whole molecule to you in its molecular detail and then we're going to simplify it down to a version that we can talk about more easily.

现在讲碱基,你不需要记住这些结构,我将给你们详述整个分子,的结构细节,然后我们把它简化为一个模板,使我们更容易讨论

耶鲁公开课 - 生物医学工程探索课程节选