流行病学的研究范围是（）

A.传染病

B.地方病

C.传染病和地方病

D.传染病和非传染病

E.疾病和健康状况

Local villagers ______the doctors with the people ______ in the bus crash.

A．assisted; wounded

B．aided; wounding

C．help; wounding

D．saved; wounded