56 B) Well-educated people tend to work longer.

　　57 B) A rapid technological advance.

　　58 A) Economic growth will slow down.

　　59 C) Even wealthy people must work longer to live comfortably in retirement.

　　60 D) Skills are highly valued regardless of age.

　　61 C) The decline of the grain yield growth.

　　62 A) Their self-sufficiency is vital to the stability of world food markets.

　　63 D) They focus more on the increase of animal feed than human food feed grains.

　　64 D) The world will be able to feed its population without increasing farmland.

　　65 B) It is based on a doubtful assumption.