simple present - affirmative sentence negation - explanations:

simple present – negation

The English language negates a statement by using the auxiliary do. So if you don't like Coke, you don't not like Coke. Makes sense? do not (don’t) respectively does not (doesn’t) umschreibt. Wörtlich übersetzt würde der Satz „I don’t like Coca Cola.“ also „Ich tue Coca Cola nicht mögen.“ bedeuten. Etwas merkwürdig, aber mit etwas Übung kein Problem.

simple present verneinung

negation simple present

 

! Therefore, do not negate like this: I not play football. Or: I play football not.

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After the negation by does not, doesn’t the main verb loses its dangling -s.

She doesn’t like(no s) football.

The third person singular is sufficiently defined by the -s inside the auxiliary doesn't.