如图所示，ABCD为直角梯形(∠DAB=∠ABC=90°)，以AD为一边向外作长方形ADEF

把4封信投入3个信箱中的两个信箱，不同的投法有______。

必然与偶然 论说文：根据下述材料，写一篇700字左右的论说文，题目自拟。 《韩非子·五蠹》记载：战国时期宋国有一个农民，看见一只兔子偶然撞在树桩上死了，于是他便放下锄头每天在树桩旁等待，他认为

甲、乙两个机器人同时按匀速进行100m速度测试，自动记录仪表明：当甲距离终点1m时

若圆柱体的高h与底面半径r的比为4:3且侧面积为18π，则它的高h=______． A． B． C． D． E．

Bankers have been blaming themselves for their troubles in public. Behind the scenes, they have been taking aim at someone else: the accounting standard-setters. Their rules, moan the banks, have forced them to report enormous losses, and it's just not fair. These rules say they must value some assets at the price a third party would pay, not the price managers and regulators would like them to fetch. Unfortunately, banks' lobbying now seems to be working. The details may be unknowable, but the independence of standard-setters, essential to the proper functioning of capital markets, is being compromised. And, unless banks carry toxic assets at prices that attract buyers, reviving the banking system will be difficult. After a bruising encounter with Congress, America's Financial Accounting Standards Board (FASB) rushed through rule changes. These gave banks more freedom to use models to value illiquid assets and more flexibility in recognizing losses on long-term assets in their income statement. Bob Herz, the FASB's chairman, cried out against those who "question our motives." Yet bank shares rose and the changes enhance what one lobby group politely calls "the use of judgment by management." European ministers instantly demanded that the International Accounting Standards Board (IASB) do likewise. The IASB says it does not want to act without overall planning, but the pressure to fold when it completes its reconstruction of rules later this year is strong. Charlie McCreevy, a European commissioner, warned the IASB that it did "not live in a political vacuum" but "in the real world" and that Europe could yet develop different rules. It was banks that were on the wrong planet, with accounts that vastly overvalued assets. Today they argue that market prices overstate losses, because they largely reflect the temporary illiquidity of markets, not the likely extent of bad debts. The truth will not be known for years. But bank's shares trade below their book value, suggesting that investors are skeptical. And dead markets partly reflect the paralysis of banks which will not sell assets for fear of booking losses, yet are reluctant to buy all those supposed bargains. To get the system working again, losses must be recognized and dealt with. America's new plan to buy up toxic assets will not work unless banks mark assets to levels which buyers find attractive. Successful markets require independent and even combative standard-setters. The FASB and IASB have been exactly that, cleaning up rules on stock options and pensions, for example, against hostility from special interests. But by giving in to critics now they are inviting pressure to make more concessions. Bankers complained that they were forced to ______.

A． B． C． D． E．

某车间开展劳动竞赛后，每人1天多做10个零件

两条平行直线l1，l2分别过点P(-2，-2)，Q(1，3)，并且这两条直线之间的距离为d，如果这两条直线各自绕点P，Q旋转并始终保持平行

设Sn是等差数列{an}的前n项和，S5=3(a2+a8)，则的值为______． A． B． C． D． E．1

不等式(1+x)(1-|x|)＞0的解集为 ．

设{an}是等比数列，Sn=10，S2n=30，则S6n-S5n等于______．

|a-b|=|a|+|b|成立，a、b∈R，则下列各式中一定成立的是______。

五名选手在一次知识竞赛中共获得404分，每位选手的得分互不相等(每位选手的得分都是整数)

已知等比数列{an}中，各项都是正数，且成等差数列，则 A． B． C． D． E．

分解因式：x4+2x3-3x2-4x+4=______．

已知f(x)=2x，g(x)=4x，则方程f(g(x))=g(f(x))的解为______．

如图是一个棱长为1的正方体表面展开图．在该正方体中，AB与CD确定的截面面积为______． A． B． C．1 D． E．

D关于实数x的不等式|x-1|+|x-2|≥a2-a+1(a∈R)的解集是R

While fossil fuels—coal, oil