Student or Learner
When do you produce the es/s suffix as z, s, or iz?
'z' never takes the place of where 'es' or 's' should be even though it sounds like it should.
There's a phonetic dictionary I use that lists all the suffix endings for 50,000 English words. No rules, just look up the word and it will show you how to spell the word with the suffix ending. "Gabby's Wordspeller & Phonetic Dictionary". Until we learn and memorize all the rules, it helps to have a mother's little helper. Especially when learning English as a Second Language...I cannot even imagine what that would be like.