General meaning:
* The primer provided a basic understanding of the subject before the more advanced material.
* She used a primer to seal the wood before painting it.
* The primer on rocket science was fascinating, but I still need to learn more.
Specific meaning (related to cosmetics):
* I always use a primer before applying my foundation to create a smoother canvas.
* The primer helped to minimize the appearance of my pores.
* The makeup artist recommended a mattifying primer for my oily skin.
Specific meaning (related to guns):
* The primer ignites the gunpowder, causing the bullet to fire.
* The gun misfired because the primer was damaged.
* Replacing the primer is an essential part of gun maintenance.
Specific meaning (related to DNA):
* Scientists use primers to amplify specific sequences of DNA.
* The polymerase chain reaction relies on primers to target and copy specific DNA segments.
The correct usage depends on the context. Be sure to consider the specific meaning of "primer" when using it in a sentence.