今天我们学第九课。

Today we'll learn the ninth lesson.

youdao

今天下午，我女儿复习了第九课。

My daughter reviewed lesson 9 this afternoon.

youdao

第九课她连续不断地读了半小时。

She went on reading Lesson 9 for half an hour.

youdao

So, if you can flip your lecture notes over and just write on the blank space, we're going to cover electronegativity first here, and specifically, you can go back and fill this in to your lecture 9 notes, if you want to stay organized, but I just suggest just writing it on lecture 10 notes now and going back.

因此，请大家把讲义翻到背面,就在空白处做一下笔记，我们要先讲一讲电负性，特别提醒一下，大家可以,回到第九课的讲义并把这些记在那里，如果你想保持条理性的话,但是我建议大家先写在第十课的讲义上,回去再记到第九课的讲义上。

麻省理工公开课 - 化学原理课程节选