True or false: concluding a speech by returning to the introduction is often a great way to end.

That statement is false.
Concluding a speech need to be done by summarizing the main point that the speaker wanted to tell the audience.
Returning to the introduction will destroy the flow of the speech and make the audience become confused on what message the speaker actually wants to convey.

Afine-grained igneous rock forms as a result of slow cooling.