1. Is there something I can do to help you?
2. Is there something I can help you?

3. Is there something I can help you
with?

4. Is there something I can help you
do?

5. Is there some
way I can help you?

One of the forum gentlemans answered my question like above.
I don't know why 'with' 3 is necessary, and why 2 without 'with' is weird.
And please tell me if there are similar cases like a preposition supplement in 3.
Thank you