What does adding と after an adverb do?


For example, what is the difference between ゆっくり and ゆっくりと?




Well, there is not much difference between the two. Using the と in this
instance really just "Emphasizes" ゆっくり. It is hard to quantify in English, but
sort of has the feeling of trying to make the preceding more clearer in the
emphatical sense.

Eg, these two statements are almost identical in meaning "Study Hard", but the
bottom one just has that extra little bit of meaning, like you would say in
English "Study really hard".

> しっかり勉強しなさい。

and

> しっかりと勉強しなさい。

