属于长江流域，而且完全位于我国第二级阶梯上的省区是 A．青海 B．西藏 C．贵州

—He didn't go to the lecture this morning, did he?                            

—               .Though he was not feeling very well.               [ ]

A. No, he didn't                   

B. Yes, he did               

C. No, he did                      

D. Yes, he didn't

An Intranet is (71) the application of Internet technology within an internal or closed user group．Internets are company and not do not have a (72) connection to the Internet．Usedproperly an Internet is highly effective corporate tool，capable of regularly (73) information toempower the workforce with the information needed to perform their roles．Used in this Way，Internet represent a step towards the (74) office．

A．painless

B．painness

C．paperless

D．paperness

提升什么品质对我们一生都有作用（）

A.服务

B.知识

C.工作能力

D.家庭

锅筒的作用为（）

A、净化蒸汽，组成水循环回路和蓄水

B、汇集或分配多根管子中的工质

C、在炉膛内壁上吸收高温辐射热量，提高锅炉产气量

设A为n阶实对称矩阵，B为n阶可逆矩阵，Q为n阶正交矩阵，则下列矩阵与A有相同特征值的是
(A) B^-1Q^TAQB． (B) (B^-1)^TQ^TAQB^-1．
(C) B^TQ^TAQB． (D) BQ^TAQ(B^T)^-1．