I don't think that I am adding anything new here, but this may clear up a couple of points.
In the present simple (affirmative), the form used for all persons except the third person singular of all verbs (except BE and the modals) is the same as first form/base form/bare infinitive:
I know/play/try/do/wash
you know/play/try/do/wash
we know/play/try/do/wash
they know/play/try/do/wash
In the third person singular of all verbs (except BE and the modals), an -s is added to the first form. There may be other slight changes, such as the addition of an e before the -s, but there is always an -s ending:
he knows/plays/tries/does/washes
she knows/plays/tries/does/washes
it knows/plays/tries/does/washes
the boy knows/plays/tries/does/washes
the girl knows/plays/tries/does/washes
Peter knows/plays/tries/does/washes
In the negative and interrogative form, we use the bare infinitive of the verb with the auxiliary DO. It is the auxiliary that adds the ending in the third person singular:
I/you/we/they do not know, do not play, do not try, do not do, do not wash
he/she/it/the boy/the girl/Peter does not know, does not play, does not try, does not do, does not wash
Do I/you/we/they know?, play?, try?, do?, wash?
Does he/she/it/the boy/the girl/Peter know?, play?, try?, do?, wash?
Best Answer
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