单选题已知a=1999x+2000，b=1999x+2001，c=1999x+2002，则多项式a 2 +b 2 +c 2 -ac-bc-ab的值为______

单选题两个自然数相除所得的商为39，余数4，被除数，除数，商及余数的和等于247．除数和被除数分别为( )．

单选题若将2，4，6，8，10，12，14，16，…，依次排成一行：246810121416…，则从左向右数的第101个数码是( )．

单选题设正项级数an。发散，令Sn=a1+a2+…+an，则下列结论正确的是()

单选题设函数f(x)连续，下列变上限积分函数中，必为偶函数的是______．A．B．C．D．

单选题Judge Kleinberg got it right when he made it clear that there weren't separate rules for bloggers and journalists. That's not to say bloggers are or aren't journalists—just that there shouldn't be a distinction. In other words, the same rules apply to everyone. But—and here's the tricky part—although the rules apply to people equally, we can, do, and should apply them differently to different acts. Asking whether bloggers are journalists is meaningless. What's important isn't the person but the product. If a snoopy 12-year-old girl find evidence that her town's mayor is taking bribes, then collects it, verifies it, and publishes it on her blog, that's journalism. If Waiter Cronkite writes in his diary that he planted daisies and washed the dishes that afternoon, that's not. It's what's done, not who's doing it. This isn't something that always needed to be pointed out. In the old days, you could draw a line between journalists and everyone else, just as you could draw a line between any other profession. What you did is what you were: reporter, barber, grocer, tailor, whatever. Journalists were usually hired by newspapers, magazines and radio stations. And they followed certain rules, respecting off-the-record comments, being accurate and not misquoting. Today, the Web is an essentially way to get news, and, while journalism is pretty much the same, the term "journalist" is getting a bit cloudy. That's why the question of whether bloggers are journalists keeps coming up. When anyone can publish, anyone can be a journalist. So the questions the courts need to answer is not, "Who is a journalist?" but rather, "Who is doing journalism?" That 12-year-old girl was doing it, even if she isn't in high school yet—even if she wasn't a journalist. Not being a journalist doesn't necessarily reduce the quality of the work, nor should it reduce the protections it receives. So when a question of journalists' rights comes up, we need to ask two questions. First, "What protections should journalism receive under the First Amendment?" And second, "Was the person in question performing an act of journalism?" If she is—if the work she was doing involves gathering and publishing information of legitimate public interest—then her profession doesn't matter. The idea that the line between amateurs and professionals is blurring is something we need to get used to. The Web gives the little guy the same publishing tools as the big guy. Video-editing software is inexpensive enough that the quality of amateurs equals that of many pros. But while our technology is removing age-old distinctions, our perceptions and our laws haven't quite embraced the new reality. It's time to shift our thinking.

单选题从5张100元，3张200元，2张300元的奥运预赛门票中任取3张，则所取3张中至、少有2张价格相同的概率为()．

单选题已知，则______．A．B．C．D．E．

单选题设，则f (x )在(-1 , 1) 内

单选题设随机变量X的概率密度记Y=X2和二维随机变量(X，Y)的分布函数为F(x，y)，则F(1，4)等于

单选题a=-5是齐次方程组有非零解的A.充分必要条件B.充分而非必要条件C.必要而非充分条件D.既非充分也非必要条件

单选题等差数列{a n }的前n项和为S n ，若a 4 是a 3 与a 7 的等比中项，S 8 =32，则S 10 等于______．

单选题下列反常积分收敛的是

单选题下列积分中，值为零的是______．A．B．C．D．

单选题在1至200中，既不是2的倍数，又不是3的倍数的所有整数之和是( )．

单选题圆C1：x2+y2-2mx+4y+(m2-5)=0与圆C2：x2+y2+2x-2my+(m2-3)=0相内切，则m的值是( )． A．1或2 B．-1或2 C．1或-2 D．-1或-2 E．以上结论均不正确

单选题函数的定义域为（　　）

单选题在一个平面直角坐标系中，直线l的方程为x=5，点A和B的坐标分别为(3，2)和(-1，3)．动点C在l上，则AC+CB的最小值为()．

单选题设A，B是n阶矩阵，则C=的伴随矩阵是()．

单选题设y=x 2 -x -5 ，则y"等于______。