有谁知道什么是高中起点升专科吗？

若函数 (x)=x-arctanx，则 ′(x)=_________．

作为艺术反映生活的基本形式，艺术作品的核心应该是__________。（ ）

A.艺术形象
B.艺术观念
C.艺术追求
D.艺术意蕴

If you want to stay young,sit down and have a good think．This is the research result of professor Faulkner,who says that most of our brains are not getting enough exercise and as a result,we are ageing unnecessarily soon.
Professor Faulkner wanted to find out why healthy farmers in northern Japan appeared to be losing their ability to think and to reason at a relatively early age,and how the process of ageing could be slowed down.
He set about measuring brain volumes of a thousand people of different ages and occupations．
Computer technology enabled him to obtain precise measurements of the volume of the front and side sections of the brain,which relate to intelligence and emotion,and determine the human character．
Contraction of front and side parts--as cells die off--was observed in some subjects in their thirties,but it was still not evident in some sixty-and seventy-year-olds.
Faulkner concluded from his tests that there is a simple way to slow the contraction—using the head.
The findings show that contraction of the brain begins sooner in people in the country than in the towns．Those least at risk,says Faulkner,are lawyers,followed by university professors and doctors．White--collar workers doing routine work are,however,as likely to have shrinking brains as the farm worker,bus driver and shop assistant.
Faulkner's findings show that thinking can prevent the brain from shrinking．Blood must circulate properly in the head to supply the fresh oxygen the brain cells need．"The best way to maintain good blood circulation is through using the brain,"he says．"Think hard and engage in conversation．Don't rely on pocket calculators."

Faulkner's research findings are based on__.

A.a survey of farmers in northern Japan
B.tests performed on a thousand old people
C.the study of brain volumes of different people
D.the latest development of computer technology

1946年，中共决定将减租减息政策改为实现“耕者有其田”政策的文件是（）7-130

A.《井冈山土地法》
B.《兴国土地法》
C.《关于清算、减租及土地问题的指示》
D.《中国土地法大纲》