问题
单项选择题
The diversity of tropical plants in the region represents a seemingly ______ source of raw materials, of which only a few have been utilized.
A．exploited
B．controversial
C．inexhaustible
D．remarkable
答案
参考答案：C
解析： 从句意尤其是后半句，可知此题应选C“用不完的，用之不竭的”。如：an inexhaustible supply of coal用之不竭的煤炭供应。A“被开采的，被开发的”、B“争论的，争议的”和D“不平常的，非凡的，显著的”均不符合题意。