签订订货合同，根据众多货物的不同特点，可采取( )签订合同。A．直线方式 B．多种

数列{a_n}满足：an+2=an+1-an(n∈N*)，且a₂=1，若数列的前2012项之和为2013，则前2013项的和等于______．

Of Chinese secondary school students top ten heroes,Mao Zedong,ranks number one and Olympic track gold medal winner,Liu Xiang,ranks fifth,according to a survey conducted by All-China Women’s Federation (ACWF).

Late Chinese leaders,Mao Zedong and Zhou Enlai,and revolutionary martyrs,Liu Hulan and Dong Cunrui,all have remained important heroes in the eyes of Chinese teenagers aged 13 to 18.

Meanwhile,the 2004 Olympic track and field star,Liu Xiang;model police chief,Ren Changxia;Hong Kong action star,Jackie Chan,and China’s first astronaut Yang Liwei,have ascended to be the new stars among the students.

“The coexistence of old and new models in youth’s hearts reveal the new era’s character,” said Han Xiangjing,president of “China Women” magazine attached to ACWF.

The respondents also chose their parents as heroes,ranking number two.

“This reflects that young students’ selection standards of heroes have changed to be more human oriented,emotional and personalized,”Han said.

Reasons given by the surveyed students for this choice are:“parents are the people I love and indispensable to me”and“they consistently guide,encourage and support me.”

The survey was conducted in six provinces and cities across China,including Beijing,Shanghai,Henan,Shanxi,Liaoning and Hunan.Students completed 1018 questionnaires;443 polled were boys and 575 were girls.

小题1:This passage most probably appears _________.

A．in a newspaper

B．in a magazine

C．in a history book

D．in a report小题2:This passage mainly talks about _________.

A．a survey about teenagers’top 10 heroes

B．why teenagers regard their parents as heroes

C．different heroes in teenagers’eyes

D．All-China Women’s Federation小题3:How many heroes of the top 10 can be found in the passage?

A．10.

B．9.

C．8.

D．7小题4:Which of the following is NOT the reason why teenagers choose their parents as heroes?

A.Their parents are the people they love very much.

B.Their parents are indispensable to them.

C.Their parents have done something great and successful.

十七大报告指出，深化政治体制改革，必须坚持正确政治方向，以保证人民当家作主为根本，以增强党和国家活力、调动人民积极性为目标，扩大社会主义民主，建设社会主义法治国家，发展社会主义政治文明。我国推进政治文明建设必须遵循的基本方针是

A．坚持党的领导、人民当家作主和依法治国的有机统一

B．坚持国家的一切权力属于人民

C．坚持有序的政治参与

D．实行民主集中制

下列关于螺杆式制冷压缩机的说法正确的是（）

A.利用一个阳转子和一个阴转子相互啮合所组成的一对转子，在机壳内回转而完成吸气、压缩与排气的过程

B.利用叶轮高速旋转产生离心力来实现压缩过程

C.利用一旋同螺旋板和一固定螺旋板之间的空间容积的改变来实现吸气，压缩与排气的过程

D.利用转子在气缸中旋转来实现吸气、压缩与排气的过程

肝硬化病人可出现腹水的血清白蛋白至少低于

A．20g/L

B．20g/L

C．30g/L

D．40g/L

E．25g/L