Simple and direct:
* The scientist demonstrated the experiment's results to the class.
* Her actions clearly demonstrated her commitment to the cause.
With more context:
* The artist's latest exhibit demonstrated a mastery of color and composition.
* The team's performance demonstrated their ability to work effectively under pressure.
Figurative language:
* His words demonstrated a deep understanding of the issue at hand.
* Her smile demonstrated the joy she felt at the moment.
The best sentence for you will depend on the specific context and the meaning you want to convey.