Напишите следующие существительные во мн. ч.:

a) place, library, language, dress, fly, watch, clock, country, eye, bus, bush, party, ray, thief, company, Negro, mass, leaf, wolf, glass, key, box, half, life, day, play, factory, city, opportunity, colony, roof, month, journey, shelf, hero;

b) man, woman, tooth, foot, goose, child, mouse, ox;

c)postman, son-in-law, editor-in-chief, fisherman, schoolgirl, sister-in-law, text-book, pocket- knife, passer-by, statesman;