二尖瓣狭窄并有血栓栓塞时，约2／3的体循环栓塞为（）。 A.脑动脉栓塞 B.脾动脉栓

金融危机预警系统的构成主要包括哪些方面？

It has been announced by our provincial government that another two medical teams will be sent to _______ the injured people in the severe earthquake.

A．join to

B．join in

C．take part in

D．attend

After the earthquake passed away, all the villages and towns were _____. And no being was seen.

A. in ruin            B. in ruins             C. at ruins         D for ruins

标志着邓 * * 成为党的第二代中央领导集体的核心的是

A．1978年的真理标准大讨论

B．党的十二大

C．党的十一届三中全会

D．党的十一届六中全会

已知A是三阶矩阵，A的每行元素之和为3，且线性齐次方程组AX=0有通解k₁1，2．-2^T+k₂2，1，2^T，α=1，1，1^T．其中k₁，k₂是任意常数．
(Ⅰ)证明：对任意的一个三维向量β，向量Aβ和α线性相关；
(Ⅱ)若β=3，6，-3^T，求Aβ．