第18题: [单项选择]What is insomnia A. A problem nearly everyone has ever had. B. The phenomenon people stay up all night long. C. A physical disease. D. One fails to fall asleep or easily wakes up in the midnight. 参考答案:D 答案解析:[分析] 本题考查词义理解。见文章旨段对“insomnia”这一概念的阐述,可得出答案。