by repeating the child's utterance.
You repeat the child’s utterance giving the correct adult form of grammar, e.g. child says, “mummy go”; you repeat, “yes, mummy’s gone home”. Or child says “no mummy come”; you repeat “no, mummy hasn’t come yet”. Or the child says, “Boy up ladder for get cat”; you repeat, “Yes, the boy’s climbed up the ladder to get the cat down”.