đề bài: put the words into THREE groups (/s/, /z/ and /iz/)
books, doors, windows, boards, colloks, bags, pencils, desks, schools, classroms, students, teachers, couches, benshes, maps, sinks, beds,
-/iz/:......................................................................
-/s/:.......................................................................
-/z/:.....................................................................
-/iz/:couches,benshes,
-/s/:books,sinks,colloks,desks,students,maps,
-/z/:windows,boards,pencils,schools,classroms,teachers,doors,bags,beds
