单选题函数的单调递减区间为{{U}}{{/U}}。A.(-∞，-3)和(3，+∞)B.(-3，3)C.(-∞，0)和(0，+∞)D.(-3，0)和(0，3)

单选题设，则f(x，y)=____

单选题设f(x)＞0，且导数存在，则=______。A．0B．∞C．lnf'(a)D．

单选题Du Bois was a sociological and educational pioneer who challenged the established system of education that tended to restrict rather than to advance the progress of black Americans. He challenged what is called the “Tuskegee machine” of Booker T. Washington, the leading educational spokesperson of the blacks in the U. S. . As a sociologist and historian, Du Bois called for a more determined and activist leadership than Washington provided. Unlike Washington, whose roots were in southern black agriculture, Du Bois’s career spanned both sides of the Mason-Dixon Line. He was a native of Massachusetts, received his undergraduate education from Fisk University in Nashville, did his graduate study at Harvard University, and directed the Atlanta University Studies of Black American Life in the South. Du Bois approached the problem of racial relations in the United States from two dimensions: as a scholarly researcher and as an activist for civil rights. Among his works was the famous empirical sociological study, The Philadelphia Negro: A Social Study, in which he examined that city’s black population and made recommendations for the school system. Du Bois’s Philadelphia study was the pioneer work on urban blacks in America. Du Bois had a long and active career as a leader in the civil rights movement. He helped to organize the Niagara Movement in 1905, which led to the National Association for the Advancement of Colored People (NAACP), established in 1909. From 1910 until 1934, Du Bois edited The Crisis, the major journal of the NAACP. In terms of its educational policy, the NAACP position was that all American children and youth should have genuine equality of educational opportunity. This policy, which Du Bois helped to formulate, stressed the following themes: (1) public schooling should be free and compulsory for all American children; (2) secondary schooling should be provided for all youth; (3) higher education should not be monopolized by any special class or race. As a leader in education, Du Bois challenged not only the tradition of racial segregation in the schools but also the accommodationist ideology of Booker T. Washington. The major difference between the two men was that Washington sought change that was evolutionary in nature and did not upset the social order, whereas Du Bois demanded immediate change. Du Bois believed in educated leadership for blacks, and he developed a concept referred to as the “talented tenth”, according to which 10 percent of the black population would receive a traditional college education in preparation for leadership.

单选题曲线y=x(x-1)(2-x)与x轴所围图形面积可表示为A．B．C．D．

单选题有些列关于数项级数的命题(1)若≠0，则必发散；(2)若un≥0，un≥un+1(n=1，2，3，…)且必收敛；(3)若收敛，则必收敛；(4)若收敛于s，则任意改变该级数项的位置所得到的新的级数仍收敛于s．其中正确的命题个数为

单选题设n为正整数，在1与n+1之间插入n个正数，使这n+2个数成等比数列，则所插入的n个正数之积等于______。A．B．(1+n)nC．(1+n)2nD．(1+n)3n

单选题曲线

单选题不等式的解集为______。A．[-1，0)B．[-1，+∞)C．(-∞，-1]D．(-∞，-1]∪(0，+∞)

单选题设A，B为n阶可逆矩阵，则______.

单选题货币在执行某种职能时，可以是观念上的货币，而不必是现实的货币，这种情况属于______。 A．价值尺度职能 B．流通手段职能 C．贮藏手段职能 D．支付手段职能

单选题设{a n }为等比数列，a n ＞0(n=1，2，…)，且a 5 a 6 =81，则log 3 a 1 +log 3 a 2 +…+log 3 a 10 =______．

单选题设，则f(x，y)在(0，0)处()

单选题函数的单调减少区间为

单选题设A，B，C是，n阶矩阵，并满足ABAC=E，则下列结论中不正确的是 (A) ATBTATCT=E. (B) BAC=CAB. (C) BA2C=E. (D) ACAB=CABA.

单选题制造一种产品，原来每件成本是100元，由于连续两次降低成本，现在的成本是81元，则平均每次降低的百分率是______。

单选题设f(x)是连续函数，且则F'(x)等于______．

单选题某单位有职工40人，其中参加计算机考核的有31人，参加外语考核的有20人，有8人没有参加任何一种考核，则同时参加两项考核的职工有( )．

单选题下列反常积分①②③④中收敛的是

单选题社会主义初级阶段是指______。 A．资本主义向社会主义的过渡时期 B．社会主义向共产主义的过渡阶段 C．从社会主义建立到现代化完全实现 D．从社会主义建立到现代化基本实现