To be + infinitive verb + ing
I am walking.
You / we / you / they are walking.
He / she / it is walking.
Exceptions
Verbs ending in –e ⮕ replace –e with –ing.
Verbs ending in –c ⮕ add –king
Verbs with one syllable and one vowel* ⮕ double consonant* + ing
Verbs ending in –l ⮕ double –l
*Vowels: a, e, i, o, u
Consonants: all other letters