Part II: Read the text below, and then answer the questions. Corals, the basic structures of coral reefs, are affected by the increasing acidity (decreasing pH) of the oceans. When the ocean absorbs carbon dioxide, the carbon dioxide reacts with water and other substances to form carbonic acid. This process uses substances in the ocean that corals use to build their skeletons. So, the more carbon dioxide there is in the ocean, the harder it is for corals to build their skeletons. Ocean acidification can also destroy existing coral reefs.