单选题下列命题 ①若存在一组不全为零的数x1，x2，…，xs，使向量组α1，α2，…，αs的线性组合x1α1+x2α2+…+xsαs≠0，则向量组α1，α2，…，αs线性无关 ②若存在一组全为零的数x1，x2，…，xs，使向量组α1，α2，…，αs的线性组合x1α1+x2α2+…+xsαs=0，则向量组α1，α2，…，αs线性无关 ③向量组α1，α2，…，αs(s≥2)线性无关的充分必要条件是α1，α2，…，αs中任意t个(1≤t≤s)向量都线性无关 ④若向量组α1，α2，…，αs(s＞2)中任取两个向量都线性无关，则向量组α1，α2，…，αs也线性无关 ⑤若向量组α1，α2，…，αs中，αs不能由α1，α2，…，αs-1线性表示，则向量组α1，α2，…，αs线性无关 ⑥若向量组α1，α2，…，αs线性相关，且αs不能由α1，α2，…，αs-1线性表示，则α1，α2，…，αs-1线性相关 中正确的个数是 (A) 1个． (B) 2个． (C) 3个． (D) 4个．

单选题设，则有______．

单选题设f(x)连续，若=(A)1．(B)-1．(C)3．(D)-3．

单选题下列二次型中正定二次型是

单选题曲线y=x 3 -1在点(-2，-9)处的切线的斜率等于( )。

单选题设相互独立的随机变量X i 的分布函数为F i (x)，概率密度为f i (x)，i=1，2，则随机变量Y=max(X 1 ，X 2 )的概率密度为______．

单选题设则=()．A．B．C．D．E．1

单选题 The sources of anti-Christian feeling were many and complex. On the more intangible side, there was a general pique against the unwanted intrusion of the Western countries; there was an understandable tendency to seek an external scapegoat for internal disorders only tangentially attributable to the West and perhaps most important, there was a virile tradition of ethnocentrism, vented long before against Indian Buddhism, which, since the seventeenth century, focused on Western Christianity. Accordingly, even before the missionary movement really got under may in the mid-nineteenth century, it was already at a disadvantage. After 1860, as missionary activity in the hinterland expanded, it quickly became apparent that in addition to the intangibles, numerous tangible grounds for Chinese hostility abounded. In part, the very presence of the missionary evoked attack. They were, after all, the first foreigners to leave the treaty ports and venture into the interior, and for a ling time they were virtually the only foreigners whose quotidian labors carried them to the farthest reaches of the Chinese empire. For many of the indigenous population, therefore, the missionary stood as a uniquely visible symbol against which opposition to foreign intrusion could be vented. In part, too, the missionary was attacked because the manner in which he made his presence felt after 1860 seemed almost calculated to offend. By indignantly waging battles against the notion that China was the sole fountainhead of civilization and, more particularly, by his assault on many facets of Chinese culture per se, the missionary directly undermined the cultural hegemony of the gentry class. Also, in countless ways, he posed a threat to the gentry's traditional monopoly of social leadership. Missionaries, particularly Catholics, frequently assumed the garb of the Confucian literati. They were only persons at the local level, aside from the gentry, who were permitted to communicate with the authorities as social equals. And they enjoyed an extraterritorial status in the interior that gave them greater immunity to Chinese law than had ever been possessed by the gentry. Although it was the avowed policy of the Chinese government after 1860 that the new treaties were to be strictly adhered to, in practice implementation depended on the wholehearted accord of provincial authorities. There is abundant evidence that cooperation was dilatory. At the root of this lay the interactive nature of ruler and ruled. In a severely understaffed bureaucracy that ruled as much by suasion as by might, the official almost always a stranger in the locality of his service, depended on the active cooperation of the local gentry class. Energetic attempts to implement treaty provisions concerning missionary activities, in direct defiance of gentry sentiment, ran the risk of alienating this class and destroying future effectiveness.

单选题已知，A*是A的伴随矩阵，若r(A*)=1．则a=A.3．B.2．C.1．D.1或3．

单选题向量组a1=(1，-1，2，4)T，a2=(0，3，1，2)T，a3=(3，0，7，14)T，a4=(1，-2，2，0)T，a5=(2，1，5，10)T的极大线性无关组不能是( )。 A．a1，a2，a4 B．a2，a3，a4 C．a1，a4，a5 D．a1，a3，a5

单选题已知x，y满足关系式6x—8y—13=0，则的最小值为()．

单选题[2012年10月]如图，长方形ABCD的长和宽分别为2a和a，将其以顶点A为中心顺时针旋转60°。则四边形AECD的面积为24—。(1)a=；(2)△AB'B的面积为。

单选题一条长为1200m的道路的一边每隔30m立一根电线杆，另一边每隔25m栽一棵树，如果在马路入口与出口处刚好同时有电线杆与树相对而立，那么整条道路上两边同时有电线杆与树相对而立的地方共有( )处．

单选题设函数f(x)(x∈)为奇函数，且f(x+2)=f(x)+f(2)，则f(5)=______．A．0B．1C．D．5