most verbs: add -ing to the infinitive
verbs ending in -e: drop the final -e and add -ing
verbs ending in -ie: chance -ie to y and add -ing --> -ying
doubling of consonants: b, d, l, g, m, n, p, r, t are doublet only when: at the end, consonant at the ent of the wort follows on vowel, syllable is stressed
verbs ending in -c: chance -c to -ck