56、B It will protect them from sunburn

　　57、A I is ineffecitive in preventing melanomas

　　58、D Daily application of sunscreen helps reduce the incidence of melanomas

　　59、C It is not based on sirect observation of the subjects

　　60、A A Using both covering up and sunscreen.

　　61、B well-educated people tend to work longer.

　　62、B A rapid techonological advwnce.

　　63、A Economic groth will slow down.

　　64、C Even wealthy people must work longer to live comfortably in retirement .

　　65、D Skills are highly valued regardless of age.