I can't think of any reason to say no. Why not! We are humans. Male & female are humans not two different breed of aliens from another planets.
Can a girl and guy be just friends?
Yes they can. My best friend is a woman, we do everything together and sometimes her husband tags along.
Sure they can ! I have quite a few female friends. I enjoy their company and sometimes we do things together. But I keep my heart for a special lady and the rest are just friends.
Sure. I've had plenty of female friends. They're pretty much like people. >:-/
It is hard to say what will happen in all cases, but it is extremely difficult to do. The makeup of male and female has a natural attraction that is only escalated when a regular association is developed. I remember when younger we all had play "brothers and sisters" and I can remember what always happened. Close association with the opposite sex has a way of ending up being more than just "friends".
Not according to Harry Burns in When Harry met Sally, but I know they can. I have more friends that are guys than I do that are girls.