题干

证明:函数f(x)=
1
x
2
在(﹣∞,0)上是增函数.
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答案(点此获取答案解析)

证:f′(x)=
2
x
3
,∵x<0,∴ <

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完形填空。阅读下列短文,从每小题所给的A、B、C、D四个选项中选出一个最佳选项。

    After his parents' meeting , Wang Jiaming , 14 , from Beijing knows that he will face invisible(看不见的)“enemies”—“other excellent students”.

    “Look at such and such a student . You and he are taught by the same teachers . Why couldn' t you be as 1 as him ?”his mother would say .

    Many students hear 2 words from their parents . After the parents' meeting , their parents begin to 3 them with other students , especially those who are praised by teachers .

    “I want to encourage my child to 4 them ,”explained Li Shulan , a mother of a 14-year-old boy from Xi'an , Shanxi .However , many children , like Wang , don' t like it .

    “I feel very 5 and sometimes even‘hate'those students ,”Wang said .Parents have good intentions(意图), but in fact they could 6children's selfesteem(自尊),said Li Ying,a  psychological (心理的) teacher at Xiamen Hubin Middle School in Fujian . If children feel hurt , they should let parents know it .“You can choose a relaxing occasion , for example , over the dinner , and tell your parents your feelings ,”Lin said .“Also , some articles online explain 7 it could be bad for children . You may want to show such articles to your parents .”

    It's not all bad , though . Liu Jiayang , 13 , from Taizhou , Zhejiang said students could take the chance to learn to be open-minded .

    “I find the students that my mom talks about really have strong 8 that I don' t have . I take them as examples and try to 9 with them ,”she said .

    “During the process(过程), always keep in mind that you' re unique(特别的). Never 10 heart ,”Lin added .