After his uncle died ，the young man _____the beautiful estate with which he changed from a poor man to a wealthy noble ．

Many _______will be opened up in the future for those with a university education ．

John says that his present job does not provide him with enough ______for his organizing ability.

It is estimated that ，currently, about 50，000 species become _____every year ．

His wife has been _______a lot of pressure on him to change his job.

设随机变量 ( Ｘ, Ｙ) 服从二维正态分布，且 Ｘ与Ｙ不相关， f ( x) f ( y) X Y 分别表示 Ｘ，Ｙ的概率密度， 则在Ｙ＝y的条件下， Ｘ的条件概率密度f X|Y （X|Y） 为（）

某人向同一目标独立重复射击, 每次射击命中目标的概率为 p(0< p<1), 则此人第 4 次射击恰好第 2 次命中目标的概率为（）

设矩阵则A与B（）

设向量组线性无关，则下列向量组线性相关的是（）

设曲线 L:f(x,y)=1(f(x,y) 具有一阶连续偏导数 ) ，过第II 象限内的点M和第IV象限内的点N，T为L上从点M到点N的一段弧，则下列小于零的是（）