Which river makes up a large part of the boundary between mexico and the united states?
mississippi river
rio grande
amazon river
rio de la plata

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.

What gigantic island is primarily in the arctic circle?

Astudent in a skill or trade training program who is learning by gaining experience is a(n) a. mentor b. volunteer c. colleague d. apprentice