Here's why:
* Subject: The subject of the sentence is "Dental veneers," which is plural.
* Verb: The verb "covers" is singular.
Corrected Sentence:
Dental veneers made of porcelain or plastic can cover chipped, stained, or crooked teeth.
Explanation of the correction:
* We changed the verb "covers" to "cover" to match the plural subject "Dental veneers."
* We also added commas to separate the adjectives "chipped," "stained," and "crooked."