A．It develops more easily in centenarians not actively engaged.
B．It is now the second leading cause of death for centenarians.
C．It has had no effective cure so far.
D．It calls for more intensive research.
A．They care more about their physical health.
B．Their quality of life deteriorates rapidly.
C．Their minds fall before their bodies do.
D．They cherish their life more than ever.
A．They are focused more on attraction than love.
B．They were done by his former colleague at Yale.
C．They were carried out over a period of some thirty years.
D．They form the basis on which he builds his theory of love.