Exercise 12 :
1.D ; 2.C ; 3.A ; 4.B ; 5.D
Exercise 14 :
1.B ; 2.C ; 3.A ; 4.A ; 5.A
Exercise 15 :
/s/ : lamps , desks , sinks , laptops , toilets , books , clocks , apartments , chopsticks.
/iz/ : houses , fridges , dishes.
/z/ : rooms , posters , buildings , beds , wardrobes , tables.