Which sentence is correct when comparing things. For example:
"Display do not have black spot"
"Display does not have spot"
- "Theorem do not have a proof"
- "Theorem does not have a proof".
"The display (singular) DOES not have..."
"The cows (plural) DO not have..."
This is similar to most verbs, including "Go":
The cows go home together. The cow goes home by himself.
When the subject is plural (or the pronouns I/we/they), the verb typically does not end in an "s" (or "es"). "Dogs go..."
When the subject is singular, or (the pronouns he/she/it), the verb ending is usually "s" or "es": "He goes..."
Most verbs, including Go, Try, Do, Play, Want, Need, Take, Eat, Sleep -- are conjugated with an "s/es" ending for singular subjects.
"Do" is just a little unusual, because the pronunciation for the singular and plural subjects are different. That is unlike "Go" and all the other verbs listed above, for which adding "s/es" at the end does not change the sound of the vowel. "Go/Goes" have the same long "O" sound. "Do/Does ('Doo'/'duhz')" sound different.