It can be seen from the passage that the earth’s supply of natural medicines． A.may never be exhausted B.is surprisingly big C.may be dropping rapidly D.is as rich as ever
A.A.may B.is C.may D.is
【参考答案】
C 借助常识判断c是答案。如果借助原文：利用题于中的核心结构theearth’ssupplyofnaturalm......