DOUBLE CONSONANTS WHEN ADDING -ING,-ED,-ER,OR -ESTWHEN

3.Double consonants when adding -ing,-ed,-er,or -estwhen:• the verb stem contains one vowel one consonant in one syllablegrab grabbing grabbedtrip tripping tripped• the verb stem contains two or more syllables with one vowel consonant in the final stressedsyllableprefer preferring preferredcontrol controlling controlled(but not travel, traveling, traveled because the stress is on the first syllable)• the suffix -eror -estis added to one-syllable adjectives ending in one vowel consonantbig bigger biggesthot hotter hottest• adding -lyto an adjective ending in ljoyful joyfullysuccessful successfully