我要预习一下明天要教的东西。

Wǒ yào yùxí yíxià míngtiān yào jiāo de dōngxi.

I need to prepare the material I will teach tomorrow.

老师叫我们先预习下一节课的词汇。

Lǎoshī jiào wǒmen xiān yùxí xià yì jié kè de cíhuì.

The teacher told us to preview the vocabulary for the next lesson.

如果你先预习课文，上课就更容易听懂。

Rúguǒ nǐ xiān yùxí kèwén, shàngkè jiù gèng róngyì tīngdǒng.

If you preview the text first, it will be easier to understand the class.