Doubling the final consonants
Rule1: If a word has more than 1 syllable and this word ends in a consonant after a single vowel, you need to double the consonant before adding -ing or -ed.
•occur > occurring/ occurred
•commit> committing/ committed
•prefer> preferring/ preferred
•control> controlling/ controlled
Rule 2: words of more than 1syllable only have their consonants doubled when the second syllable is stressed.
•o/pen [you can’t double the ‘n’ because the second syllable is not the primary stressed part]
•offer> offering/ offered
Rule 3: If the vowel in front is unstressed, or spelling with two vowels, do not double the consonant.
•enter > entered/ entering
•visit> visiting/ visited
•develop> developing/ developed
•shout> shouting/ shouted