如图所示，AB是一质量为m的均匀细直杆，A端靠在光滑的竖直墙壁上，B端置于水平地

---Peter was killed in a car accident!

---      I talked with him yesterday morning.  

A  What a pity!  B.I beg your pardon.  C. Sorry to hear that.  D. Is that so?

世界上三种东西最宝贵——知识、粮食和友谊。我们要想取得优异的成绩，除了20%决定于智力因素外，还应该[ ]

①培养浓厚的学习兴趣      

②养成良好的学习习惯  

③在竞争中学会合作        

④把所有时间都用在学习上

A、①②③   

B、①②④   

C、②③④   

D、①③④

我国《产品质量法》的适用主体范围包括( )。

A．制造商

B．销售商

C．进口商

D．以上三者皆包括

An analyst does research about market efficiency. Which of the following statements least likely explains why a market mispricing may persist（）

A. Arbitrage is encouraged to produce riskless profits.

B. A price discrepancy is insufficient large to leave the investor with a profit.

C. Short selling is limited or restricted.

网络商务信息收集后，需要进行整理，______不属于信息整理工作。

A．明确信息来源
B．信息分类
C．信息鉴别
D．信息形式变换