4. Put the words in the plural form.
1. toy, city, hero, piano, chief, bath, shelf, roof, pen, window, wall, week, clock,
watch, dress, party, bus, leaf, fox, glass, eye, key, mouth, bush.
2. foot, ox, fox, man, woman, month, mouse, child, ship, goose, deer, cheese,
sheep.
3. crisis, phenomenon, passer-by, sister-in-law, postman, son-in-law, fisherman,
text-book, stateman, editor-in-chief.
4. knowledge, trousers, people, cattle, police, scissors, fish, sugar.