II Put the words into the THREE groups (/s/, /z/ and /iz/).
books, doors, windows, boards, clocks, bags, pencils, desks, schools, classrooms, students, teachers, couches, benches, glasses, brushes, maps, sinks, beds, calculators, villas, lamps
-/iz/: ......................................................................................................................................
-/s/: ......................................................................................................................................
-/z/:
/iz/: couches, benches, glasses, brushes.
/s/: books, clocks, desks, students, maps, sinks, lamps.
/z/: doors, windows, boards, bags, pencils, schools, classrooms, teachers, beds, caculators, villas.