Study the information about spelling in the past perfect continuous.
Past perfect continuous (spelling tips for adding the ending -ing to a verb):
|Add -ing to most verbs.
play – playing
|For verbs that end in -e, remove the -e and add -ing.
ride – riding
|For verbs that end in -ie, change the -ie to -y and add -ing.
die – dying
|For verbs with last syllables being stressed 'consonant-vowel-consonant' combinations, double the last letter before adding -ing.
beg – begging
They were tired. They had been playing for 2 hours.
My friends were happy. They had been riding horses for 3 hours.