But people have only begun to take a real interest in acid rain and to conduct scientific investigations into it during the past 20 years, once sufficient concern had been generated by acid rain's obvious harmful effects on the environment.
但人類真正對酸雨發生興趣和做科學性探討，卻與「不見棺材不掉淚」的個性有關；也就是近廿年來，在酸雨已對人類生活環境造成顯著影響後，才引起人們關注和重視。