If you've taken a foreign language class in school, you know how frustrating it is when the teacher starts talking TOO FAST for you to separate the words and think about their meanings.
When you were just a tot, learning to talk and read, there was a reason you read simple things (out loud) like, "See Spot go. Go, go, go."
Another way to say "See Spot go" would be...."Look toward the horizon and you'll notice a large black and white canine ambulating rapidly into the distance." But when you were "Dick and Jane" age, that would have been too much...too fast...for you to comprehend.
Your dogs are the same way. In fact, they have the mental capacity of two- or three-year-old children. When we speak to them, we must articulate clearly and simply. If you are chaining several commands together, separate each word so your dog has a moment to ponder the meaning of each command.
An example: correction for a sit-stay infraction. The verbal correction might be, "No! Sit. Stay." Three distinct requests for threee separate concepts. "No!" (Stop doing whatever you're doing.) "Sit." (Lower your butt to the floor.) "Stay." (Don't move your butt from that spot on the floor.)
And yet, so many dog owners will spit out these three commands like, "Nositstay!" Or "No, uh-uh. No, no. Sit, sit, sit. Now st-stay. Sit, sit. Stay. Stay." Chances are, the dog gave up trying to understand all this after the first "no."
Try this, without your dog around:
Say "No!" and take a breath.
Say "Sit," and take a breath.
Say "Stay," and take a breath.
Hear yourself? Now try it again, but make it "flow" a bit more:
Remember the "speak slowly" concept whenever you're introducing a new command or a new concept. Let the dog absorb it and react to it. You'll notice more understanding in his face, and more cooperation in his actions.