preposition
used to indicate the place where someone or something is
used to indicate the person or thing toward which an action, motion, or feeling is directed or aimed
used to indicate something that is being tried or attempted
because of or in reaction to (something)
used to indicate an activity
used to indicate a situation or condition
a - used to indicate position on a scale or in a series
b - used to indicate a rate
used to indicate an age or time
used to indicate the method by which something is done
a - used in phrases like at best, at worst, etc., to indicate a possible result or condition that is considered best, worst, etc.
b - used in phrases like at its best, at its worst, etc., to indicate that something or someone is as good, bad, etc., as possible
at it
doing some activity
at that
where it's at
where (someone) is at
US