已知向量a=(2x-3,1),b=(x,-2),若a•b≥0则实数x的取值范围是

题型:选择题

问题:

已知向量
a
=(2x-3,1),
b
=(x,-2),若
a
b
≥0
则实数x的取值范围是(  )
A.[-
1
2
,2]
B.(-∞,-
1
2
]∪[2,+∞)
C.[-2,
1
2
]
D.(-∞,-2]∪[
1
2
,+∞)
考点:一元二次不等式及其解法用坐标表示向量的数量积
题型:选择题

任务型阅读(共5小题,每小题2分,满分10分)

在第76至80题中,Celia, Enoch, Martina, Brian和Derek准备选择一所大学就读。阅读下面六所大学的介绍(选项A、B、C、D、E和F),选出符合各人需求的最佳选项,选项中有一项是多余选项。

1  Celia’s mother is a nice kindergarten nurse and when she was very young she was in close touch with children. With time passing by, she has got interested in early children education and has made up her mind to follow her mother.

2   Enoch is from Texas of US whose grandparents were black slaves who worked on a south plantation(大种植园). He has learned some about his ancestors’ miserable past and wants to study the Black People in US. Also, he hopes the university will offer the dormitory equipped with the Internet so that he can have a good connection with his friends.

3   Martina’ mother, as well as many of her relatives, is an active member of the Women’s Right Movement. Influenced by them, Martina thinks highly of their work and takes part in their activities from time to time. She has decided to do more studies about the Women’s Right Movements after she graduates from school.

4  Brian expects to head for an exciting and challenging major which makes humans live better and longer when he enters university. What’s more, he is energetic and eager for an environment which is convenient for outdoor activities such as hiking , rafting so that he can enjoy a long life.

5   With the coming of IT age, Derek is determined to find a college or university where he can have cost-effective life-long learning with high quality so as so meet the needs of a changing and developing world. Then, can you guess what his head-for major may be?

A. Most exciting and full of opportunity, challenges and self-discovery, this university combines urban cultural lifestyle with small town safety. It has a mild climate and is ideal for outdoor activities such as hiking, rafting. Its main majors are Education, Engineering, Physical / Life Sciences and so on.

B. It is a community college located next to a famous resort town offering technical programs for students. Its task is to provide a comprehensive, student-centered college education and use a variety of teaching methods in the classroom. It owns the following majors: Music, Early Childhood Education, Economics and so on.

C. Our college is to achieve and maintain recognized excellence in education, service and leadership within a changing world. It is cost-effective life-long learning and prepares students for great careers. Its majors are Information Technology, Professional and Career Development Programs, Social Sciences and some others.

D. As a state-assisted private university, it was founded in 1929. The campus has grown significantly in size and scope. Residence halls are equipped with Internet access. The university offers 117 different majors including Art, Environmental Sciences, Black Affairs Studies Program, Industrial and Manufacturing Engineering and so on.

E. This University has earned a reputation for providing quality education to meet the needs of students preparing for new careers of tomorrow. It is close to the city of Detroit , with a safe environment. The following majors are offered: Philosophy, Psychology, Women’s Studies Program, Social Work, etc.

F. In our university, students are treated as individuals, and are helped to be good at academics, art, music. Personalized instruction in a small classroom setting is possible. Students interact one-on-one with highly qualified professors. Our main majors are: Math / Computer Sciences, Social Sciences / Humanities and so on.

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在我国实施的“西气东输”工程中,西部地区的天然气被输送到缺乏能源的东部地区。天然气与煤相比,从热学角度分析它突出的优点是____________;从环保角度分析它突出的优点是_____________。(天然气、煤的热值分别为1.14×108J/kg、3×107J/kg)

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设计师设计运动休闲风格腰带时不能应用以下哪种材料()。

A.皮革

B.帆布

C.塑料

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