When words change form, there are certain spelling patterns and pronunciation changes that regularly occur. Familiarity with these patterns can improve your writing.
Sometimes ending consonant sounds like t (/t/), hard c (/k/), s (/s/), and d (/d/), change to /sh/, /ch/, or /zh/ sounds when words change their forms.
Example:
pollute > pollution
admit > admission
Example:
optic > optician
pediatric > pediatrician
Example:
discuss > discussion
obsess > obsession
Example:
suspend > suspension
proceed > procession
Example:
quest > question
suggest > suggestion
Example:
explode > explosion
decide > decision
Sometimes vowels change their pronunciations when base words change forms.
Example:
sane > sanity
decide > decision
Example:
impose > imposition
specialize > specialization
Example:
agile > agility
photograph > photography
Sometimes the silent letters of certain base words are sounded, or pronounced, in different forms of the words.