What morpheme is associated with Brown's Stage 4, learned at ages 40-46 months?

In Brown's Stage 4, typically occurring between the ages of 40 to 46 months, children acquire the regular past tense morpheme "-ed." This morpheme allows children to express actions that have occurred in the past, indicating a significant step in their grammatical development. At this stage, children start to use more complex sentence structures, and the addition of the regular past tense enhances their ability to narrate past events and experiences.

Understanding the use of the regular past tense is crucial for language development, as it reflects children's growing awareness of time reference in language. This stage signifies an important milestone in the acquisition of morphology, allowing children to add layers of meaning to their speech.

The other morphemes mentioned are important too, but relate to different developmental stages. The regular plural "-s," for example, and the possessive "-'s" are typically acquired earlier, while the uncontractible copula appears later in development. This context helps clarify the significance of the regular past tense "-ed" in Brown's Stage 4.