使不等式成立的一個必要不充分條件是（    ）

    A.     B．   C． D． ，或

在等比數(shù)列的值為（    ）                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

    A.9           B．1  C．2    D．3

以雙曲線的中心為頂點，右焦點為焦點的拋物線方程是（    ）

  A.      B．     C．    D．

現(xiàn)將10個參加2009年全國高中數(shù)學(xué)競賽的名額分配給某區(qū)四個不同學(xué)校，要求一個學(xué)校1名，一個學(xué)校2名，一個學(xué)校3名，一個學(xué)校4名，，則不同分配方案種數(shù)共有 （    ）

A.43200               B．12600              C．24          D．20

定義運算：，將函數(shù)的圖象向左平移（）個單位，所得圖象對應(yīng)的函數(shù)為偶函數(shù)，則的最小值為（    ）

A.             B．            C．            D．

在空間給出下列四個命題：

①如果平面內(nèi)的一條直線垂直于平面內(nèi)的任意一條直線，則⊥；

②如果直線與平面內(nèi)的一條直線平行，則∥；

③如果直線與平面內(nèi)的兩條直線都垂直，則⊥；

④如果平面內(nèi)的兩條直線都平行于平面，則∥．其中正確的個數(shù)是

Ａ．　　　　　    Ｂ．　　　　　  Ｃ．　　　　     Ｄ．

用數(shù)1、2、3、4、5可以組成沒有重復(fù)數(shù)字，并且比20000大的五位偶數(shù)共有（    ）

A.48個      B．36個         C．24個           D．18個

已知，直線與直線互相垂直，則的最小值等于（    ）

A．1    B．2    C．    D．

已知、是橢圓長軸的兩個端點，是它短軸的一個端點，如果與的夾角不小于，則該橢圓的離心率的取值范圍是（    ）

A．    B．    C．     D．

已知是定義在上的增函數(shù)，函數(shù)的圖像關(guān)于點對稱，若對于任意的，不等式恒成立，則當(dāng)時，的取值范圍是（    ）

A．（3，7）    B．（9，25）    C．（13，49）    D．（9，49）