已知函数f(x)=-x2+4x+a，x∈[0，1]，若f(x)有最小值-2

A.条件(1)充分，但条件(2)不充分．B.条件(2)充分，但条件(1)不充分．C.条件(1)和条件(2)单独都不充分，但条件(1)和条件(2)联合起来充分．D.条件(1)充分

某车间接到一批任务，需要加工6000个A型零件和2000个B型零件。车间共有224名工人

A．20 B．21 C． D． E．

Why do people read negative Internet comments and do other things obviously painful? Because humans have an inherent need to 1 uncertainty according to a recent study in em>Psychological Science/em>. The new research reveals that the need to know is so strong that people will 2 to satisfy their curiosity even when it is clear the answer will 3 In a series of four experiments, behavioral scientists at the University of Chicago Booth School of Business and the Wisconsin School of Business tested students' willingness to 4 themselves to unpleasant stimuli in an effort to satisfy curiosity. For one 5 , each participant was shown a pile of pens that the researcher claimed were from a previous experiment. The twist? Half of the pens would 6 an electric shock when clicked. Twenty-seven students were told which pens were electrified; another 27 were told only that some were electrified. 7 left alone in the room, the students who did not know which ones should shock them clicked more pens and incurred more jolts than the students who knew what would 8 . Subsequent experiments reproduced this effect with other stimuli, 9 the sound of fingernails on a chalkboard and photographs of disgusting insects. The drive to 10 is deeply rooted in humans, much the same as the basic drives for 11 or shelter, says Christopher Hsee of the University of Chicago, a co-author of the paper. Curiosity is often considered a good instinct—it can 12 new scientific advances, for instance—but sometimes such 13 can backfire. The insight that curiosity can drive you to do 14 things is a profound one. Unhealthy curiosity is possible to 15 , however. In a final experiment, participants who were encouraged to 16 how they would feel after viewing an unpleasant picture were less likely to 17 to see such an image. These results suggest that imagining the 18 of following through on one's curiosity ahead of time can help determine 19 it is worth the endeavor. "Thinking about long-term 20 is key to mitigating the possible negative effects of curiosity," Hsee says. In other words, don't read online comments.

六位身高全不相同的同学拍照留念，摄影师要求前后两排各三人

若k，-1，b三个数成等差数列，则直线y=kx+b必经过定点______．

旅客携带了30kg行李从首都机场乘飞机去上海，按民航规定，旅客最多可携行李20kg

在等差数列{an}中，已知a1+a2+…+a10=p，an-9+an-8+…+an=q，则该数列的前n项和Sn等于 A． B． C． D． E．

已知直线L：3x+4y-1=0，L1：2x+y-4=0，则L1关于L对称的直线L2的方程为 ．

设a2+1=3a，b2+1=3b，且a≠b，则代数式的值为______·

设m，n是小于20的质数，满足条件|m-n|=2的{m，n}共有______．

张老师到一所中学进行招生咨询，上午接受了45名同学的咨询，其中的9名同学下午又咨询了张老师

如果关于x的不等式与同解，则a______． A．不存在 B．等于-3 C．等于 D．大于 E．小于

已知3m和2n的平均数为12，2m和3n的平均数为8，则m和n的平均数为

已知，则的值为______． A． B．2 C． D．2或 E．以上答案均不正确

a，b为两个整数，已知a=36，a和b的最大公约数是4，最小公倍数是288

化简(0＜n＜1)得______．

{an}为等比数列，其偶数项所组成的新数列的前n项和则原数列的通项是 A． B． C． D．an=2×3n-1 E．

现象与本质 论说文：根据下述材料，写一篇700字左右的论说文，题目自拟。 孔子的一位学生在煮粥时，发现有脏东西掉进锅里去了。他连忙用汤匙把它捞起来，正想把它倒掉时，忽然想到