第2题: [单项选择]Some studies confirmed that this kind of eye disease was ______ in tropic countries. A. prospective B. prevalent C. provocative D. perpetual 参考答案:B 答案解析:[解析] 本题是说一些研究证实这种眼疾在热带国家很普遍。B项“prevalent普遍的,流行的”符合题意,如:The habit of travelling by aircraft is becomi