Yes.
If you're in the US it's legal. I have no clue why an 18-year-old girl would want to marry a 50-year-OLD man (well, unless it's for money), but it's legal.
As long as they are both of legal age, yes they can marry.
depends on where the girl lives......
no children should be giving consenty to children
If she wants to.
Yes, if they have the permission of the girl's parents.
No this is against the law.
If the girl has parental consent, yes.
It is legal to date a 21 year old man if you are a 17 year old girl. It is not legal to engage in certain activities with a 21 year old man as he could be prosecuted.
Not without parental permission. Lucky man, poor girl.
Yes she can.
If she has parental permission.