The document discusses the different sounds that the "-ed" ending can make when added to verbs to make the past tense. It explains that the sound depends on the final consonant of the verb. Verbs ending in voiceless consonants like t, p, f take an ed sound pronounced as /t/. Verbs ending in voiced consonants like b, d, g take an ed sound pronounced as /d/. Verbs ending in t or d take an ed sound pronounced as /ɪd/. These rules are important for connected speech when a word ending in a consonant is followed by a word starting with a vowel.