问答题Discussion of the assimilation of Puerto Ricans (波多黎各人 ) in the United States has focused on two factors: social standing and the loss of national culture. In general, excessive stress is placed on one factor or the other, depending on whether the commentator is North American or Puerto Rican. Many North American social scientists, such as Oscar Handlin, Joseph Fitzpatrick, and Oscar Lewis, consider Puerto Ricans as the most recent in a long line of ethnic entrants to occupy the lowest rung on the social ladder. (46) Such a " socio demographic" approach tends to regard assimilation as a benign process, taking for granted increased economic advantage and inevitable cultural integration, in a supposedly egalitarian context. However, this approach fails to take into account the colonial nature of the Puerto Rican case, with this group, unlike their European predecessors, coming from a nation politically subordinated to the United States. (47) Even the "radical" critiques of this mainstream research model, such as the critique developed in Divided Society, attach the issue of ethnic assimilation too mechanically to factors of economic and social mobility and are thus unable to illuminate the cultural subordination of Puerto Ricans as a colonial minority. In contrast, the "colonialist" approach of island based writers such as Eduardo Seda- Bonilla, Manuel Maldonado-Denis, and Luis Nieves-Falcon tends to view assimilation as the forced loss of national culture in an unequal contest with imposed foreign values. There is, of course, a strong tradition of cultural accommodation among other Puerto Rican thinkers. The writings of Eugenio Fernandez Mendez clearly exemplify this tradition, and many supporters of Puerto Rico's commonwealth status share the same universalizing orientation. (48) But the Puerto Rican intellectuals who have written most about the assimilation process in the United States all advance cultural nationalist views, advocating the preservation of minority cultural distinctions and rejecting what they see as the submission of colonial nationalities. This cultural and political emphasis is appropriate, but the colonialist thinkers misdirect it, overlooking the class relations at work in both Puerto Rican and North American history. They pose the clash of national cultures as an absolute polarity, with each culture understood as static and undifferentiated. (49) Yet both the Puerto Rican and North American traditions have been subject to constant challenge from cultural forces within their own societies, forces that may move toward each other in ways that cannot be written off as mere "assimilation. " Consider, for example, the indigenous and Afro-Caribbean traditions in Puerto Rican culture and how they influence and are influenced by other Caribbean cultures and Black cultures in the United States. (50) The elements of compulsion and inequality, so central to cultural contact according to the colonialist framework play no role in this kind of convergence of racially and ethnically different elements of the same social class.

问答题求，其中D：x2+y2≤π2．

问答题设A为n阶矩阵，λ1和λ2是A的两个不同的特征值，x1．x2是分别属于λ1和λ2的特征向量．试证明：x1+x2不是A的特征向量．

问答题已知曲线y=ax 3 +bx 2 +cx在点(1，2)处有水平切线，且原点为该曲线的拐点，求a，b，c的值，并写出此曲线的方程．

问答题求下列极限：

问答题设f(x)在[0,1]连续，在(0,1)可导，且f(0)=0，f(1)=1，求证：ξ≠η∈(0,1)使得

问答题判别下列函数的奇偶性：

问答题求级数的和函数．

问答题设二维随机变量(X，Y)的概率密度为(Ⅰ)求PX＞2Y；(Ⅱ)求Z=X+Y的概率密度fz(z)．

问答题一民航班车上有20名旅客，自机场开出，旅客有10个车站可以下车，如到达一个车站没有旅客下车就不停车，以X表示停车次数，求E(X)(设每位旅客下车是等可能的)．

问答题求线性方程组的通解．

问答题设xe-x是f(x)的一个原函数，求。

问答题设函数f(x)在x=1的某邻域内有定义，且满足|f(x)-2e x |≤(x-1) 2 ，研究函数f(x)在x=1处的可导性.

问答题将函数展开成x的幂级数，并指出其收敛区间．

问答题设f(x)在[a，b]上可导，f" + (a)·f" - (b)＜0．证明：存在一点ξ∈(a，b)，使f"(ξ)=0．

问答题y=xlnx的极值与极值点．

问答题设a＞0，讨论方程ae x =x 2 根的个数．

问答题设z=f(x，y)是由方程z-y—x+xe z-y-x =0所确定的二元函数，求dz．

问答题证明：a×b=c×d，a×c=b×d，则a-d与b-c共线。

问答题设B～A*，求B+2E的特征值．