What is included in Brown's Morphemes Stage 4?

Brown's Morphemes Stage 4 marks an important developmental phase in children's language acquisition. This stage is characterized by the emergence and use of certain grammatical morphemes that enhance their verbal communication skills. Among these is the uncontractible copula, which refers to the forms of the verb "to be" that cannot be shortened or contracted (e.g., "she is" instead of "she's").

The presence of the uncontractible copula indicates that the child is beginning to understand more complex sentence structures and is able to use the verb "to be" in contexts where it functions as the main verb, demonstrating an increased awareness of subject-verb agreement. Children at this stage start to grasp the concept of linking a subject to a complement using forms of "to be" without contraction.

While other morphemes listed might appear in other stages (such as the present progressive -ing and the possessive -'s in earlier stages), the uncontractible copula is specifically attributed to Stage 4 of Brown's morphemes, showing that a child's language development is progressing toward more sophisticated grammatical usage.