過原點(diǎn)且傾斜角為的直線被圓所截得的弦長為

A．           B．            C．             D．

函數(shù)的定義域是

    A． B．    C． D．                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

命題“存在，使得”的否定是

A．不存在，使得         B．存在，使得

C．對任意，都有           D．對任意，使得

已知全集,，則

A．            B．          C．         D．

已知函數(shù)．

（Ⅰ）若函數(shù)在上為增函數(shù)，求實(shí)數(shù)的取值范圍；

（Ⅱ）當(dāng)且時，證明： . 

已知橢圓：的左、右焦點(diǎn)分別為、，橢圓上的點(diǎn)滿足，且△的面積為．

（Ⅰ）求橢圓的方程；

（Ⅱ）設(shè)橢圓的左、右頂點(diǎn)分別為、，過點(diǎn)的動直線與橢圓相交于、兩點(diǎn)，直線與直線的交點(diǎn)為，證明：點(diǎn)總在直線上.

已知數(shù)列的前項和為，且．

（Ⅰ）求數(shù)列的通項公式；

（Ⅱ）設(shè)，，

求使恒成立的實(shí)數(shù)的取值范圍．

設(shè)，函數(shù)滿足．

（Ⅰ）求的單調(diào)遞減區(qū)間；

（Ⅱ）設(shè)銳角△的內(nèi)角、、所對的邊分別為、、，

且， 求的取值范圍．

為了參加2013年市級高中籃球比賽，該市的某區(qū)決定從四所高中學(xué)校選出人組成男子籃球隊代表所在區(qū)參賽，隊員來源人數(shù)如下表：

該區(qū)籃球隊經(jīng)過奮力拼搏獲得冠軍,現(xiàn)要從中選出兩名隊員代表冠軍隊發(fā)言．

（Ⅰ）求這兩名隊員來自同一學(xué)校的概率；

（Ⅱ）設(shè)選出的兩名隊員中來自學(xué)校甲的人數(shù)為，求隨機(jī)變量的分布列及數(shù)學(xué)期望．

已知函數(shù).

（Ⅰ）若，求函數(shù)的單調(diào)區(qū)間和極值；

（Ⅱ）設(shè)函數(shù)圖象上任意一點(diǎn)的切線的斜率為，當(dāng)的最小值為1時，求此時切線的方程.