Do you know the man who sat next to me at Nam’s birthday party last night?

You know the man who sat next to me at Nam’s birthday party last night, don’t you?

You know the man which sat next to me at Nam’s birthday party last night, don’t you?

You know the man who sat next to me at Nam’s birthday party last night, do you?

You knew the man who sat next to me at Nam’s birthday party last night, don’t you?