Given the task definition, example input & output, solve the new input case.
In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Example: The Inheritance Cycle is a series of fantasy books written by Christopher Paolini.
Output: The Inheritance Cycle is a tetralogy of young adult high fantasy novels written by American author Christopher Paolini.
The output sentence elaborates on the input sentence without changing its general meaning e.g. "tetralogy of young adult high fantasy novels".

New input case for you: The differences between perennial , intermittent , and ephemeral streams are not exact and can change if different measures are used by different groups .
Output:
The boundaries between perennial , intermittent , and ephemeral channels are not defined , and subject to a variety of identification methods adopted by local governments , academics , and others with a need to classify stream-flow permanence .