Main is used with these nouns:
achievement, act, actor, actress, advantage, agent, aim, altar, ambition, area, argument, artery, aspect, asset, attraction, attribute, bathroom, bedroom, body, building, campus, cause, centre, challenge, challenger, chamber, character, characteristic, city, clause, competitor, complaint, component, concern, conclusion, consequence, consideration, contender, contention, contributor, corridor, course, courtyard, criterion, criticism, culprit, deck, demand, desk, difference, dimension, disadvantage, discipline, dish, distinction, distributor, door, drawback, drift, effect, element, emphasis, enemy, entrance, event, exception, exit, exponent, export, faction, factor, feature, finding, flaw, flow, focus, force, foyer, function, gate, goal, hall, hallway, heading, headquarters, highlight, highway, hope, hurdle, idea, impact, impediment, impetus, implication, import, impression, incentive, indicator, ingredient, instrument, interest, issue, item, line, loser, meal, menu, message, mission, motivation, motive, object, objection, objective, obstacle, occupation, offender, office, opponent, page, part, participant, partner, party, pattern, plank, plot, post office, preoccupation, priority, problem, purpose, reason, recipient, recommendation, representative, requirement, residence, responsibility, rival, road, role, room, route, sail, section, shareholder, shopping centre, shortcoming, source, speaker, sponsor, square, stage, stair, staircase, stem, story, strand, street, stress, stumbling block, subject, supplier, support, suspect, tank, target, task, text, theme, thesis, thing, thread, threat, thrust, topic, track, trail, trend, tributary, type, value, vehicle, verb, witness, worry