【简答题】证明：

【单选题】主要组织相容性抗原属于( )

【简答题】设α，β是n维非零列向量，A＝αβ T ＋βα T ．证明：r(A)≤2．

【简答题】设A，B为n阶矩阵．(1)是否有AB～BA；(2)若A有特征值1，2，…，n，证明：AB～BA．

【判断题】算术均数一定大于中位数。

【简答题】引起质粒不相容性的主要原因是什么?

【单选题】Social Networking A large but long-in-the-tooth technology company hoping to become a bigger force in online advertising buys a small start-up in a sector that everybody agrees is the next big thing. ...

【单选题】A. As is known, we set great store by the trade relationship with the third world countries.B. We’ve never had any difficulties with our Chinese partners, and we ’ d like to make as many new contacts ...

【单选题】对于 X*=3 算术,与他等价的是( )。

【单选题】执行二进制算术加运算盘+00100111其运算结果是( )。