Can you marry him? Yes. Can you take him to the US? Not without getting him a card as well. To become a citizen by marriage means you have to marry a citizen.
Anyone can marry a US citizen, green card or not. The marriage does not automatically give any special privileges to the newly married person. The US citizen can petition for you to be permitted to apply for residency, etc. It is not necessary to be a green card holder to marry a US Citizen. It is important to stay in the US legally with proper immigration papers in order to marry a US citizen.
You can marry, but your marriage does not change your immigration status since neither of you is a US citizen.
That depends on the motives of the green card holder ;)
Immigrants and aliens can get a green card when they marry a citizen on the USA.
I had a student visa but went out of status Can i marry a green card holder and apply for a green card?"
Can a US green card holder marry a filipino and petition for a spousal visa to the US
Please answer in what states can a us citizen marry an illegal alien to get the green card
You have to apply for a green card or marry a U.S. Citizen