题目

One afternoon, I was walking with Evan on the second floor. I talked on and on and Evan walked __________ in front of me. As we turned a corner, Evan __________ me and said the ten words. “Why are you talking to me? I’m not your friend.” Those were the exact words he said to me that day. I stood there __________. He kept walking and never looked back. I __________ to my next class with tears coming up in my eyes.We __________ spoke to each other after that. I __________ into a shell, like a turtle, to hide from the world. For the rest of my time in middle school, I didn’t __________ my31．(4分)现有铜与金属镁、铁、锌中的一种组成的混合物，现欲测定其组成。 【查阅资料】镁、铁、锌皆能与稀硫酸发生置换反应，且生成+2价的可溶性金属化合物和氢气。 【实验步骤及数据】取该混合物粉末8.0 g放入烧杯中，将140.0 g 溶质的质量分数为14.0％的稀硫酸平均分四次加入该烧杯中，充分反应后，测得剩余固体质量数据记录如图： 通过计算(写出计算过程)，求： (1)该混合物粉末中铜的质量分数? (2)第三次加入硫酸充分反应后，所得溶液中溶质的质量分数是多少?