Looming over the debate about human interference in the world's boreal forests is an as yet unanswerable question: Will the effects of global warming eventually dwarf man's impact?

A、 raise to greater importance
B、 make more difficult to measure
C、 cause to appear small
D、 bring to an abrupt end

【正确答案】 C

【答案解析】dwarf的意思是“(使)变矮小”，cause to appear small“使…看起来小”与之相符。其他三项raise to greater importance“提升到更重要的位置”；make more difficult to measure“使…更难衡量”；bring to an abrupt end“草草收场"都不正确。故选C。