More and more carbon dioxide is being released into the air， the more severe global warming effects.
A. contributed to
B. to contribute to
C. contributing to
D. to be contributed to
网友回答
A. contributed to
B. to contribute to
(答案→)C. contributing to
D. to be contributed to
解析：C 考查非谓语作状语。句意：越来越多的二氧化碳被释放到空气中，导致温室效应更严重。contribute to 导致，促使。空格处为现在分词作结果状语。