And sophie has an uncanny ability of understanding. There are occasions she understand entire sentences.
She's old and arthritic, as a joke once, my mums ex said "go one sophie, take a run up" when they were going back to the ute. Well she did, this dog with all arthritis that had barely trotted for the last few years started cantering along and took an almighty leap at the ute. She hurt her legs on it because she didn't make it, but i think thats a bit too weird.
Or, for instance, our old house. It backed directly onto a paddock. so we would run the dogs there 3 times a day (we had a tiny yard at that stage) and mum went out with them one morning, she forgot her phone and started heading back, she said "wait there sophie, i've just gotta go get my phone then i'll be back" well sophie sat, she waited, while the other 3 ran madly up to the house with mum. And sophie just waited in the backyard for a couple of minutes while mum got her phone.
i think just talking sentences to your dog actually helps in the communication between you, and Buster is the BEST secret keeper i know.