This language development tip is for children in the 36-48 month age range.
When engaging in conversations with your child, listen for 4 to 6 word sentences. 36 month could sound like this "We go to park". A 48+ month old child may say "We will go to the park".
Model complete sentences using appropriate grammar. Repeat your child's dialogue and extend it. Here is an example.
Child- "We go to the park"
Parent- "Yes, we will go to the park. You seem very excited to go to the park. How do you think the dog feels about going to the park".
End your turn in the conversation with an open ended question, such as the one above. This will stimulate thought and most often a complex response.