题目

According to statistics, a man is more than twice as likely to die of skin cancer ____ a woman.   A. than           B. such              C. so                D. as   答案：D句意: 据统计, 男性死于皮肤癌的几率是女性的两倍多。本题考查倍数的表示法, 核心结构为…N times as likely to die of cancer as…, 只不过…times衍生成了more than twice两倍多, 在此more than修饰twice。  18．求函数f（x）=$\sqrt{12+{2}^{x}-{4}^{x}}$的单调区间．