阅读理解
B
    Hello!I'm Kate．I want to talk about my smart phone(智能手机)．My smart phone is white．It's from my uncle Sam．He works in New York and comes back to London every December．I like mv smart phone．It is useful.
    The school rules don't allow(允许)us to take smart phones to school,so I usually use it after school or on the weekend．When I go out with my friends，I like keeping it in my bag．So my family can call me at any time．When I don't go to school．I like to call my friends to talk to them，or ask them for help with my study．I'm not very good at math，so I put an APP(应用软件)about math in my smart phone to help me． It is fun and helpful．I also use the smart phone to do some reading，play games，and watch movies．Isn't it great?
    Sometimes smart phones are not good for people．Some people spend too much time on it．I like my smart phone and I know how to let it help me. It's my good friend．
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下列图示实验基本操作错误的是（　　）

将圆x²+y²=1上每一点的横坐标保持不变，纵坐标变为原来的2倍，得曲线C．

铁及其化合物在日常生活中有广泛应用。