The preposition "on"


1.- “I am going swimming on the weekend”
2.- “I am going swimming on next weekend”

Can I drop the preposition “on” in
the first sentence?

I don?t know if the second one
needs the preposition “on”.
Can you correct it,please?

Thanks a lot!


Sentence 1 must have a preposition. Sentence 2 can’t have it.