desperately
He longed desperately to be back at home.

secretly
They were the words she had secretly longed to hear.

always
She had always longed to travel to other countries.

for
He hated the city and longed for the mountains.

be, look, seem
That dress looks a little long to me.

grow
My hair had grown long.

extremely, fairly, very, etc.
His drive to work is fairly long.

awfully, exceptionally, incredibly
excessively, overly (esp. AmE)
At 900 pages, the book is overly long.

unusually
an unusually long pause

impossibly (esp. AmE), ridiculously
a pair of impossibly long legs

relatively
a little, slightly, etc.
enough
Are you sure two hours will be long enough?

Long is used with these nouns:
absence, afternoon, answer, arc, ascent, association, ball, bang, bath, battle, beak, bench, blast, breakfast, breath, call, campaign, career, chain, chase, chat, claw, climb, coastline, coat, column, conversation, cord, corridor, courtship, crack, curl, cut, day, debate, delay, deliberation, descent, description, detour, discussion, distance, division, document, dress, drink, drive, driveway, drop, drought, duration, ear, embrace, endurance, engagement, evening, excerpt, exile, expanse, experience, explanation, exposure, extract, eyelash, face, fang, fast, feud, fight, film, finger, fingernail, flex, flight, friendship, fringe, fuse, gallery, gap, gash, glove, gown, grass, groan, gulp, hair, hallway, handle, haul, hibernation, hike, hill, history, honeymoon, hour, howl, illness, interval, job, journey, jump, kiss, knife, labour, ladder, lapse, lease, lecture, leg, lens, letter, life, lifetime, limb, limousine, line, list, lull, lunch, mane, march, meeting, memory, minute, moment, monologue, moustache, nail, nap, neck, needle, night, nightmare, nose, odds, ordeal, ovation, overcoat, pants, parenthesis, pass, passage, path, pause, pedigree, period, piece, poem, post, process, procession, puff, pull, queue, résumé, rally, range, reach, recession, record, residence, rest, ribbon, ride, river, road, robe, round, route, row, run, saga, scar, scarf, scratch, section, sentence, separation, sequence, series, sermon, service, session, shadow, shift, shorts, shot, sickness, siege, sigh, silence, sip, skirt, sleep, sleeve, slide, slope, sniff, sock, solo, space, span, speech, spell, standing, stay, stem, stick, stint, stop, strand, stretch, stride, strike, strip, stroke, stroll, struggle, succession, summer, suspension, sweep, swig, swim, sword, syllable, table, tail, tale, talk, tenure, term, terrace, think, time, title, tongue, tour, tradition, trail, trek, trip, trousers, tunnel, underwear, vacation, valley, view, visit, vowel, voyage, wait, walk, wall, war, wavelength, way, week, weekend, while, whistle, window, wing, winter, word, year

Long is used with these adjectives:
defunct, extinct, interested, overdue

Long is used with these verbs:
believe, cease, dream, kiss, last, linger, regard, sleep, survive, wait