题目

—The concert won't start till seven. Why____ so early? —You know I don't want to be at the traffic there. It's terrible during the rush hour. A . are you leaving B . do you leave C . were you leaving D . had you left 答案：A下列物质进出细胞的过程与线粒体密切相关的是(　　)①酒精被胃黏膜吸收 ②氧气进入细胞③肾小管管壁上皮细胞吸收原尿中的Na＋ ④小肠绒毛上皮细胞吸收氨基酸A. ①② B. ③④ C. ②③④ D. ①②③④