Final answer:
To expand the sentence 'The bears were eating the berries', one can add the subordinating conjunction 'while' and details of 'when' by referring to the time of day and 'where' by mentioning a specific location, such as 'near the tranquil riverbed'.
Step-by-step explanation:
The sentence 'The bears were eating the berries' can be expanded using a subordinating conjunction and additional information related to 'when' and 'where'. One way to do this is by adding the subordinating conjunction 'while' and the 'when' and 'where' details. Here is an example: While the sun was setting, the bears were eating the berries near the tranquil riverbed.
The use of 'while' introduces the time element, indicating that the bears' eating took place concurrently with the sun setting. The phrase 'near the tranquil riverbed' provides a location, completing the expansion of the original sentence by utilizing subordinating conjunctions and clauses of time and place.