Write the plural of the following nouns:
Piano, shelf, army, potato, safe, wolf, cliff, wife, schoolboy, schoolchild, leaf, life, factory, knife, man, roof, photo, toy, tomato, class, room, copy, book, note, house, wife, news, paper, home, land, mother, country, student, typist, writer, pilot, doctor, officer, architect, actor, actress, painter, sailor, dentist, teacher, mechanic, locksmith, driver, composer, shop-assistant.