题目

I told you that you shouldn't waste your time playing the computer games,_____________? A. didn't I    B. did I    C. should you    D. shouldn't you   答案：A此题考查反意疑问旬的使用。用手握住一个汽水瓶悬在空中，瓶子保持竖直，如果增大握力，则摩擦力 ．（填“增大”、“减小”或“不变”）．如果物体表面2m2的面积上受到的压强是400Pa，那么该面1m2面积上受到的压强是 Pa．