单选题|3x+2|+2x2-12xy+18y2=0，则2y-3x=______．A．B．C．0D．E．

单选题已知等腰直角三角形ABC和等边三角形BDC(如图18-1)，设△ABC的周长为，则△BDC的面积是( )．

单选题设f(x)=ln2+e3，则f"(x)=______A．B．0C．ln2+e3D．(ln2+3e2)

单选题若(am+1．bn+2)．(a2n-1．b2m)=a5b3，则m+n的值为( )。 A．1 B．2 C．3 D．-3

单选题设____

单选题同宿舍的4名MBA研究生中，至少有两人的生日在同一个月的概率为()．

单选题设集合则A∩B的元素个数为()．

单选题Are teens and young adults more narcissistic (自恋的) today than in the past? That's the view of a California researcher who studies (1) people. In her new book, The Narcissism (2) : Living in the Age of Entitlement, psychologist Jean Twenge of San Diego State University and (3) W. Keith Campbell of the University of Georgia say research shows (4) young people today have "narcissistic traits" than in (5) generations. Such traits, Twenge says, include a very. (6) and inflated sense of self, which is (7) by a preoccupation with MySpace, Facebook and YouTube. "We've been on this self-admiration cultural (8) for a long time," Twenge says. (9) Twenge's take on today's young people isn't universal. Studies by other researchers, including Canadian (10) Dr. Kali of the University of Western Ontario, have used the same data but found (11) results. "They put a different (12) on it," Kali says. Twenge's studies have found more narcissistic traits and a (13) rate of increase among college students today, but Kali found that students' narcissism was (14) greater in 2006 than in 1976. Twenge's most recent paper studied the same data as Kali--more than 20 000 college students from 2002 to 2007. (15) researchers used the Narcissistic Personality Inventory to measure narcissistic (16) and findings by both have been (17) in peerreviewed journals. Twenge's book (18) just a month after The Mirror Effect : How Celebrity Narcissism Is Seducing America, a book co-written by behavioral (19) Drew Pinsky, (20) suggested that a celebrity-obsessed culture is causing more narcissism.

单选题设A，B为n阶矩阵，则下列结论正确的是______．

单选题若随机事件A与B相互独立，而且P(A)=0.4，P(B)=0.5，则P(AB)=( )

单选题某自来水公司的水费计算方法如下：每户每月用水不超过5吨的，每吨收费4元，超过5吨的，每吨收取较高标准的费用．已知9月份张家的用水量比李家的用水量多50%，张家和李家的水费分别是90元和55元，则用水量超过5吨的收费标准是______元/吨．

单选题点x=0是函数的______。

单选题若f"(x)连续，则下列等式正确的是______

单选题______．A．eB．e-4C．D．

单选题如果向量组α 1 ，α 2 ，…，α s 的秩为r，则下列命题中正确的是

单选题车间共有40人，某次技术操作考核的平均成绩为80分，其中男工平均成绩为83分，女工平均成绩为78分．该车间有女工______．

单选题某国际科研合作项目成员由11个美国人、4个法国人和5个中国人组成．现从中随机选出两位作为成果发布人，则此两人不属于同一个国家的概率为()．

单选题当x→0时，下列无穷小中最高阶的是

单选题=______．A．B．C．D．E．

单选题若f(x)为偶函数，则是______