primer

It's best to use a coat of primer before the top coat.

最好在刷表面漆前先刷一层底漆。

Primers are used under foundation to keep your make-up in place for hours.

在粉底前使用妆前乳可以让妆容保持数小时。

I bought a primer on photography to help me understand the basics of taking good pictures.

我买了一本关于摄影的入门书，以帮助我理解拍好照片的基础知识。