题目

Just because they make more money than I do, _____ they seem to look down on me. A. so                        B. and C. but                       D. 不填   答案：D按英语语法，because 为从属连词，用以引导原因状语从句，它表明整个句子为复合句。日常生活和生产活动中，摩擦有时是有益的，有时是有害的．请你举一个增大有益摩擦的实例：鞋底上有花纹鞋底上有花纹．