A clear introduction that identifies the issue being addressed in a speech also summarizes the argument.
presents evidence.
establishes a plan.
makes a claim.

What evidence does the writer give to support his argument about coral reefs? a) he speaks of the activities of coral polyps. b) he describes the composition of the great barrier reef. c) he emphasizes the ways in which coral reefs are fragile. d) he points out the ways that scientists do research on the reefs.

As water is cooled from 4 c to 0 c its density

Whats the biggest sea in the world?