Repeating the last syllable or word

When every you say a sentence to E or A and they repeat it, they only repeat the last syllable or word. It’s quite funny.

For example I migh say “Abby, do you want to go outside?” and she’ll say “outside”. Or, Emily, “Say supercalafragolisticexpialidocious” and Emily will say “docious” 😀 Always just the last little bit. 😀