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问题 单项选择题

函数f（x）=|2x-1|在点处的导数是（）

A．0

B．

C．2

D．不存在

答案

参考答案：D

解析：

绝对值求导的关键是去绝对符号，然后根据分段函数求导数． 因为

所以 因为，所以在处的导数不存在．

完形填空

Julie enjoyed reading when young. She grew up in    小题1:   key middle school in her city,    小题2:   her parents both taught Chinese. That meant she was surrounded by either teachers who were busy teaching or students who    小题3:    (devote) to their studies. So she developed her love of    小题4:   .

Her interest    小题5:   reading also benefited from the fact that    小题6:   parents only let her watch half an hour of TV a day. She learned to use her mind and imagination to entertain    小题7:  . It’s not really    小题8:  (surprise) that reading became her vocation. When not reading she enjoyed watching films, walking and relaxing with her friends. Reading brought her much    小题9:  (please) and she never wanted to stop learning. Not only did reading enrich her knowledge    小题10:   it improved her learning scores.
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判断题

随机找一些消费者，依照自己的喜好对3～4个样品进行排序，称为偏爱性调查测试。
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