The author of this passage is mainly concerned with______.

A．Nowadays most people believe they can have fairly good health.
B．Human life involves a great deal of pain and suffering.
C．Most of us are aware of the full value of health.
D．Ancient people believed that health was more expensive than anything else.

A．In the past, bones might be used to decide why people fell ill.
B．In pre-industrial societies priests sometimes treated patients by singing.
C．Modern medicine is so complicated that sociology no longer has a place in it.
D．There were only two roles in an elementary medical system, the patient and the one who tried to cure him.