已选分类
理学数学
单选题若点(0，1)是曲线y=ax3+bx2+c(a≠0)的拐点，则______． A．a=1，b=-3，c=1 B．a为任意值，b=0，c=1 C．a=1，b=0，c为任意值 D．a，b为任意值，c=1
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? (A) 2 steps above (B) 1 step above (C) the same place (D) 1 step below (E) 2 steps below
单选题
单选题A four-character password consists of one letter of the alphabet and three different digits between 0 and 9, inclusive. The letter must appear as the second or third character of the password. How many different passwords are possible?
单选题Exactly three years before the year in which Anna was born, the year was 1980 x. In terms of x, on Anna's twentieth birthday, the year will be (A) 1977+x (B) 1997+x (C) 2003-x (D) 2003+x (E) 2006+x
单选题Inthemultiplicationproblemabove,F,G,andHrepresentuniqueodddigits.Whatisthevalueofthethree-digitnumberFGF?
单选题函数的可去间断点为______。A.x=0，1B.x=1C.x=0D.无可去间断点
单选题等差数列an)中，a5＜O．a6＞0，且a6＞|a5|,Sn是前n项之和．则( )． A．S1，S2，S3均小于0，而S4，S5，…均大于0 B．S1，S2，…，S5均小于0，而S6，S7，…均大于0 C．S1，S2，…，S9均小于0，而S10，S11，…，均大于0 D．S1，S2，…，S10均小于0．而S11，S12．…均大于0 E．以上结论均不正确
单选题一批救灾物资分别随16列货车从甲站紧急调到600公里以外的乙站，每列车的平均速度都为125公里/小时．若两列相邻的货车在运行中的间隔不得小于25公里，则这批物资全部到达乙站最少需要的小时数为( )． A．7.4 B．7.8 C．8 D．8.2 E．8.4
单选题设直线nx+(n+1)y=1(n为正整数)与两坐标轴围成的三角形面积Sn(n=1，2，…，2009)，则S1+S2+…+S2009=()．
单选题设收益函数为R(Q)=150Q-0.01Q2. 当产量Q=100时，其边际收益是______． A．149 B．148 C．147 D．145
单选题A child withdraws from his piggy bank 10% of the original sum in the bank. If he must add 90￠ to bring the amount in the bank back up to the original sum, what was the original sum in the bank? (A) $1.00 (B) $1.90 (C) $8.10 (D) $9.00 (g) $9.90
单选题
单选题Anumberofbrickswerepurchasedtobuildafireplace,atacostof40centseach,butonlyofthemwereneeded.Iftheunused190brickswerereturnedandtheircostrefunded,whatwasthecostofthebricksusedtomakethefireplace?(A)$76(B)$228(C)$304(D)$414(E)$570
单选题一个公司的程序员的平均工资是x，统计员的平均工资是y，问程序员与统计员加到一块的平均工资是否小于?(1)程序员多于统计员(2)y-x=4,200
单选题设数列{Sn}单调增加，a1=S1，an=Sn-Sn-1(n=2，3，…)，则数列{Sn}有界是数列{an}收敛的______。
A.充分非必要条件
B.必要非充分条件
C.充分必要条件
D.既非充分也非必要条件
单选题If x is an even integer and y is an odd integer, then which of the following is an even integer?
单选题
单选题X+2Y=16，X，Y为自然数，问X=? (1)X＞Y (2)X＞4，y＞4
单选题Tom reads at an average rate of 30 pages per hour, while Jan reads at an average rate of 40 pages per hour. If Tom starts reading a novel at 4: 30, and Jan begins reading an identical copy of the same book at 5: 20, at what time will they be reading the same page?