题目

Last week my youngest son and I visited my father at his new home in Tucson, Arizona. He moved there a few years ago, and I was eager to see his new place and meet his friends. My earliest memories of my father are a tall, handsome, successful man devoted to his work and his family, but uncomfortable with his children. As a child I loved him. He seemed unhappy with me unless I got straight A’s and unhappy with my boyfriends if their fathers were not as “successful” as he was. Whenever I went out with him on weekends, I used to struggle to think up things to say, feeling on guard. On the 17、王璐同学在进行“粗盐提纯”实验时，发现最后得到的食盐晶体的质量比加入的粗盐的质量少很多，试帮她分析一原因？