A．they cover the whole story of the former US president.
B．the assassin used to live in the former Soviet Union.
C．they are the only official documents released about Kennedy.
D．they solved the mystery surrounding Kennedy's assassination.

A．increased slowly.
B．decreased gradually.
C．stayed steady.
D．become unpredictable.

A．Business conditions have worsened in the past three months.
B．The past three months have seen a declining trend in job offers.
C．The rise of unemployment rate in some sectors equals the fall in others.
D．The unemployment rate in all sectors of the economy remains unchanged.