【题目】Scientists have warned that coral reefs are likely to become the world’s first ecosystem ______ because of global warming.
A.to disappearB.disappearingC.disappearedD.having disappeared
在线课程【答案】A
【解析】
考查非谓语动词。句意：科学家警告说，由于全球变暖，珊瑚礁很可能成为世界上第一个消失的生态系统。当被修饰词前有序数词修饰时，用不定式作后置定语，故A项正确。