Whom do you want to write to?
= Who would you like to write to?
想做某事：want to do sth.= would like to do sth.
写信给某人：write to sb.
Whom do you want to write to?
= Who would you like to write to?
想做某事：want to do sth.= would like to do sth.
写信给某人：write to sb.