A．How the survival skills of the early people influenced their diets.
B．This need to learn how to save money.
C．The increasingly complex relationship between values and the use of money.
D．The difficulty of trading larger and larger amounts of goo

A．Check out a chemistry book.
B．Make copies of all the pages in the book.
C．Put a notice on the bulletin board.
D．Look for a copy of the book on the reserve shel