单选题打印一页文件，甲出错的概率为0.04，乙出错的概率为0.05，从两人打印的文件中各取一页，其中恰有一页有错的概率为______

单选题有以下命题：①②③④则以上命题中正确的个数是

单选题如果关于x的不等式与同解，则a()．

单选题已知等差数列{an}中，a7+a9=16，a4=1，则a12的值是______ A.15 B.30 C.31 D.64 E.以上答案均不正确

单选题一项机械加工企业，用4台A型机床，5天可以完成，用4台A型机床和2台B型机床，3天可以完成，用3台B型机床和9台C型机床，2天可以完成。若3种机床各取一台工作5天后，剩下A、C型机床继续工作，还需要______天可以完成作业 A.1 B.2 C.3 D.4 E.5

单选题若x≠y，且两个数列：x，a1，a2，y和x，b1，b2，b3，y各成等差数列，那么A．B．C．D．E．2

单选题若a为9的平方根，b为-64的立方根，则a+b的所有可能值为( )．

单选题设随机变量X，Y相互独立，X，Y的概率分布分别如下则P(X2+Y2≤4)=______A．B．C．D．1．

单选题，A=αβT，则A的秩R(A)=______。A.1B.2C.3D.4

单选题Trees that ______ the view of the oncoming traffic should be cut down. A. block B. inhibit C. revise D. alter

单选题下列广义积分收敛的是()。

单选题如下图所示，则三角形数阵第n行(n≥2)的第2个数是______A．n2-n+2B．n+1C．D．E．n2+1

单选题Compared with IBM, Microsoft is a mere young company. Founded in 1975, it rose swiftly to dominate the world of personal computing with its Windows operating system and Office suite of word-processing and other productivity tools. But the company is now showing some worrying signs of middle-age fatigue. In particular, it is struggling to find a growth strategy that will enthuse disappointed shareholders. Complaint are understandable. Since Steve Ballmer took over from Bill Gates as chief executive in 2000, Microsoft's share price has decreased and the company has lost its reputation as a tech trend-setter. It has been left behind in hot areas such as search and social networking by younger companies, some of which love to thumb their noses at their older rival. Eric Schmidt, the executive chairman of Google, recently proclaimed that leadership in the tech world had passed from Microsoft and others to a "Gang of Four" fast-growing, consumer-oriented businesses: Google, Apple, Amazon and Facebook. Few would object to that. The question is: what，if anything, can Microsoft do to change it? In at least some respects, the company appears to be suffering from similar ailments to those that laid IBM low before Lou Gerstner was hired in 1993 to get it back on its feet. These include arrogance bred of dominance of a particular area-mainframe computers at IBM, personal computers at Microsoft—and internal fiefs that hamper swift change. As IBM's experience shows, recovery in the tech world is possible. And some observers see encouraging signs of progress at Microsoft. Sarah Rotman Epps of Forrester, a research firm, reckons that Windows 8, a forthcoming version of Microsoft's operating system, could be a serious competitor to Google's Android on tablet computers if the company can get it to market next year．Microsoft is also in far better shape financially than IBM was at its lowest point, so it can afford to splash out on acquisitions such as its recent $8.5 billion purchase of Skype, an internet-phone and video-calling service. That bet and an alliance with Nokia in mobile phones show that Microsoft is trying to bulk up in promising areas. Yet sceptics worry that such initiatives are not the product of an comprehensive strategic vision, but are instead temporary moves designed to calm critics who fear Microsoft is drifting downwards. David Einhorn, a prominent hedge-fund manager whose fund holds shares in Microsoft, has publicly called for a change at the top of the firm, arguing that Mr Ballmer is "stuck in the past". So far, the company's board, chaired by Mr Gates, has backed its chief executive. But if IBM's history is a guide, Microsoft may yet end up jettisoning its leader.

单选题已知实数的整数部分为x，小数部分为y，求=______

单选题长方体的三个相邻面的面积分别为2、3、6，这个长方体的顶点都在同一个球面上，则这个球面的表面积为______

单选题假设总体X的方差DX存在，X1，…，Xn是取自总体X的简单随机样本，其均值A．B．C．D．