第6题: [单项选择]On a Windows screen, there will roll down many more buttons when you hit the "Tools" button. A. cast B. caste C. cascade D. cataract 参考答案:C 答案解析:动词辨析。roll(使某物)滚动:The ball rolled down the hill.球滚下了山。cascade(使)瀑布般地落下:Her golden hair cascaded down