Suffixes
-s suffix
The  morpheme  -s  of  the  3rd  person  singular   (he  works), of  the  noun  plural  (books),  of
the  genitive  (John‟s)  and  of  the  contraction  of  is  or  has  (he‟s)  is  pronounced  in  three
different ways depending on the sound of the preceding consonant:
ɪz   after sibilant consonants:  s   ʃ   tʃ   dʒ
slices    /slɑɪsɪz/    brushes  /brʌʃɪz/  
churches  /tʃɜːtʃɪz/     wages    /weɪdʒɪz/
s     after unvoiced consonants: /f/ /k/ /p/ /t/ 
packs    /pæks/    rates    /reɪts/
laughs    /lɑːfs/    taps    /tæps/  
12
z     in other cases    
boys    /bɔɪz/    girls    /gɜːlz/  
clothes    /kləʊðz/     John‟s    /dʒɒnz/
Some unvoiced sounds,  θ  and  f , become voiced when the -s  suffix is added.
Compare:
bath    /bɑːθ/  baths      /bɑːðz/
knife    /nɑɪf/    knives      /nɑɪvz/
Exercise 16 Write the sound /s/, /z/ or /ɪz/ next to the following words.
1. judges    _____
2. lives    _____
3. plates    _____
4. classes    _____
5. breathes    _____
6. watches    _____
7. attends    _____
8. tapes    _____
9. books    _____
10. wives    _____