单选题$ 2000 is deposited into a savings account that earns interest at the rate of 10 percent per year, compounded semiannually. How much money will there be in the account at the end of one year?

单选题()

单选题设方程(lgx)1+(1+lg5)lgx+lg5=0的两个根是α和β，则αβ={{U}}{{/U}}。A．B．1+lg5C．lg5D．-50

单选题如果直线ax+2y+2=0与直线3x-y-2=0平行，那么系数a=______A．-3B．-6C．D．E．1

单选题已知α1，α2是AX=b的两个不同的解，β1，β2是导出组AX=0的基础解系，k1，k2为任意常数，则AX=b的通解是______。A．B．α1+k1(α1+α2)+k2(β1+β2)C．D．α1+k1(α1-α2)+k2(β1+β2)

单选题A person is standing on a staircase. He walks clown 4 steps, up 3 steps, down 6 steps, up 2 steps, up 9 steps, and down 2 steps. Where is he standing in relation to the step on which he started?

单选题 Passage 2 Every year, the American Lung Association (ALA) releases its annual report card on smog, and every year it gives an "F" to over half the nation's counties and cities. When ALA's "State of the Air 2002" recently came out, dozens of credulous local journalists once again took the bait, ominously reporting that their corner of the nation received a failing grade. The national coverage was no better, repeating as fact ALA's statement that it is "gravely concerned" about air quality, and neglecting to solicit the views of even one scientist with a differing view. Too bad, because this report card says a lot less about actual air quality than it does about the tactics and motives of the ALA. The very fact that 60 percent of counties were given an 'F' seems to be alarmist. This is particularly true given that smog levels have been trending downward for several decades. According to the Environmental Protection Agency (EPA) statistics, ozone, the primary constituent of smog, has declined by approximately 30 percent since the 1970s. And recent gains indicate that the progress will likely continue, even without the wave of new regulations ALA is now demanding. ALA is correct that some areas still occasionally exceed the federal standard for ozone, but such spikes are far less frequent than in the past. Even Los Angeles, the undisputed smog capital of America, has cleaned up its act considerably. Los Angeles, which exceeded federal smog standards for 154 days in 1989, has had 75 percent fewer such spikes in recent years. But an ALA-assigned "F" misleadingly implies that air quality has not improved at all. Most of the nation is currently in attainment with the current smog standard, and much of the rest is getting close. Nonetheless, ALA chose to assign an "F" to an entire county based on just a few readings above a strict new EPA standard enacted in 1997 but not yet in force. In effect, ALA demanded a standard even more stringent than the federal government's, which allows some leeway for a few anomalously high readings in otherwise clean areas. ALA further exaggerated the public-health hazard by grossly overstating the risks of these relatively minor and sporadic increases above the standard.

单选题甲跑11米所用的时间，乙只能跑9米，在400米标准田径场上，两人同时出发依同一方向，以上速度匀速跑离起点A，当甲第三次追及乙时，乙离起点还有______米．

单选题19世纪，日本外务大臣曾说：在这笔赔款以前，日本财政部门全部收人只有八千万日元。所以，一想到现在有三亿五千万日元滚滚而来，无论政府或私人都顿觉无比的富裕。使日本获得该笔巨额赔款的条约是（　　）

单选题二元一次方程组无解．(1)m＝－6；(2)m＝－9．

单选题某班同学在一次测验中，平均成绩为75分，其中男同学比女同学多80%，而女同学平均成绩比男同学高20%，那么女同学的平均成绩为( )分． (A)90 (B)88 (C)92 (D)84 (E)A、B、C、D都不正确

单选题Ifthevariables,X,Y,andZtakeononlythevalues10,20,30,40,50,60,or70withfrequenciesindicatedbytheshadedregionsabove,forwhichofthefrequencydistributionsisthemeanequaltothemedian?