The answer is:
- at first: introduces a beginning.
- still: restarts an argument after an exception.
- however: introduces an opposite position.
- finally: introduces a conclusion or summary.
Transitional words or phrases help to connect and relate ideas between sentences and paragraphs, providing cohesion to the text. They express how different parts of the text are associated with one another, so that readers can go from one idea to another more easily.