It will take a long time for the effective use of natural resources .
A. to be made
B. to make
C. being made
D. making
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(答案→)A. to be made
B. to make
C. being made
D. making
解析：考查不定式的用法：句意：实现天然气的有效使用花了很长时间。原句可改为：To make the effective use of natural gas took a long time.这里使用的是It will take +一段时间+to do sth，不定式是这句话的主语，it是形式主语，而且the effective use of natural resources和make是被动关系，选A。