单选题已知向量i，j为互相垂直的单位向量，向量a=2i+mj，若|a|=2，则m=(　　)

单选题有4个数，前3个数成等差数列，后3个数成等比数列，且第一个数与第四个数之和是16，第二个数和第三个数之和是12，则这4个数的和为______．

单选题下列选项中，根据属人管辖原则应当适用我国刑法的是( )。 A．中国公民甲在行驶于公海的中国船舶上失手致另一中国公民落水身亡的 B．外国公民乙在行驶于公海的中国船舶中向中国船员兜售毒品的 C．外国公民丙在其本国境内实施爆炸致两名中国公民身亡的 D．中国公民丁被某国有公司派往国外工作，因严重失职给国家利益造成重大损失的

单选题在区间(a，b)内，如果f'(x)=g'(x)，则下列各式一定成立的是()．

单选题若不等式|3-x|+|x-2|＜a的解集是空集，则a的取值范围是______

单选题二元函数z=(x+1)y，则______．

单选题资本主义经济危机的根源是______。 A．资本主义基本矛盾 B．社会社会化 C．固定资本更新 D．资本主义所有制

单选题设有无穷级数其中α为常数，则此级数()

单选题已知不等式ax2+4ax+3≥0的解集为R，则a的取值范围为______。A．B．C．D．

单选题设，则f"(x0)=______。

单选题设f(x)为连续函数，

单选题已知某厂每天生产z千克产品的总成本为(元)，要使产品的平均成本最小，每天应生产该产品( )． A．132千克 B 140千克 C．150千克 D．156千克 E．160千克

单选题行列式|D|非零的充分条件是( )。 (A) D的所有元素非零 (B) D至少有n个元素非零 (C) D的任意两行元素之间不成比例 (D) 以D为系数行列式的齐次线性方程组有唯一解

单选题German Chancellor Angela Merkel won over German voters in the Federal Election on Sept. 27. Can she now be won over by a French charm offensive (1) at repairing the relationship that was once at the heart of Europe? That's the question being asked in Paris, (2) top government officials are (3) talking about their desire to rekindle closer ties (4) their neighbors across the Rhine. (5) the end of World War II the Franco-German relationship has been the motor of European integration, the (6) force behind the creation of the European Union and, more recently, the introduction of the euro. But the ardor has (7) in this decade, particularly under Merkel, who has regularly struggled to (8) her irritation with French President Nicolas Sarkozy's grandstanding. Sarkozy, (9) , has often been impatient with what he (10) Merkel's lack of resolve. The sometimes (11) personal rapport is a long way from the public shows of affection their predecessors staged, particularly Helmut Kohl and FranCois Mitterrand, who movingly held (12) in 1984 in a Verdun cemetery. There's been tension on (13) , too. Charles Grant, director of the London-based think tank Centre for European Reform, points out that France and Germany have been (14) on issues from how best to reflate their economies during the economic (15) to the smartest strategies for dealing with Russia. But influential movers in France are now (16) to put the relationship back on a friendlier footing. In a recent paper French think tank Institute Montaigne (17) an ambitious agenda for the two nations, (18) that a new impetus is needed if Europe's voice is to be heard in a world (19) of big new players, such as Brazil and India, and at a time when President Obama seems fax more (20) with China and the rest of Asia than with America's traditional allies in Europe.

单选题公有制为主体、多种所有制经济共同发展，是我国社会主义初级阶段的一项基本经济制度。决定实行这一制度的理论依据是______。 A．生产力发展和生产关系性质 B．发展市场经济和扩大对外开放 C．社会主义性质和初级阶段国情 D．所有制结构和分配结构

单选题快慢两列火车长度分别为160米和120米，它们相向行驶在乎行轨道上，若坐在慢车上的人见整列快车行驶过的时间是4秒，那么坐在快车上的人见整列慢车驶过的时间是( )秒．

单选题设，则A.x=0与x=1都是f(x)的第一类间断点．B.x=0与x=1都是f(x)的第二类间断点．C.x=0是f(x)的第一类间断点，x=1是f(x)的第二类间断点．D.x=0是f(x)的第二类间断点，x=1是f(x)的第一类间断点．

单选题设D为有界闭区域，z=f(x，y)在D上二阶连续可偏导，且在区域D内满足：则______．

单选题设，则有______

单选题等于______A．arcsinxB．C．arcsinb-arcsinaD．0