下列安全措施不正确的是（）

组成地壳的化学元素中，含量较多依次排列的是（ ）

    After giving a talk at a high school, I was asked ____ (pay) a visit to a special student. An ____ (ill) had kept the boy home, but he had expressed an interest ____ meeting me. I was told it would mean a great deal to him, so I agreed.

    The thirteen-year-old, ____ had muscular dystrophy（肌肉萎缩症）, wanted to meet me because I was a gold-medal power lifter, and I knew how to deal with difficulties.

    I spent over an hour talking to him. Never once ____ he complain or ask, “Why me?” He spoke about going for his dreams. ____ (obvious), he knew what he was talking about. He didn't mention his classmates had made fun of him because he was ____ (disable). He just talked about his hopes for the future. When we had finished ____ (talk), I pulled out ____ first gold medal I had won and put it around his neck. He looked at it for a moment, then ____ (take) it off and handed it back to me. He said, “Someday when I get to the Olympics and win my own medal, I will show it to you.”