So in terms of the first step of skeletal structure, this is actually going to be easier because we don't have a central atom, we just have carbon and nitrogen here.

对于第一步画出骨架，其实比刚才更容易,因为我们没有一个中心原子，我们这里只有碳和氮两个原子。

麻省理工公开课 - 化学原理课程节选

I would first of all, congratulate you for taking the first step of starting to learn that process.

我会首先祝贺你踏出了学习语言的第一步，

学第二外语的时候 - SpeakingMax英语口语达人

And in terms of thinking about it for organic chemistry or if you're interested in thinking about the mechanism maybe by which it is toxic, a first step would be to draw its Lewis structure.

而为了在有机化学中思考它,或者如果你对它,有毒的机理感兴趣的话，第一步要做的应该就是画出它的路易斯结构。

麻省理工公开课 - 化学原理课程节选

The first step is we had to be able to take this circular DNA and cut it to create a site for our new gene to be added.

第一步是切割环形DNA,以创造出一个整合新基因的位点

耶鲁公开课 - 生物医学工程探索课程节选

the first step in any Lewis structure is drawing the skeletal structure.

画任何路易斯结构第一步,都是先画出它的骨架。

麻省理工公开课 - 化学原理课程节选