上海市2021研究生报考条件要求有哪些?

根据思维任务的性质、内容和解决问题的方法可以将思维分为哪几类？( )

A.直观动作思维
B.形象思维
C.逻辑思维
D.分析思维

设总体X的概率密度为
　　
　　其中μ是已知参数，σ>0是未知参数，A是常数.X1，X2，…，Xn是来自总体X的简单随机样本.
　　(Ⅰ)求A；
　　(Ⅱ)求σ的最大似然估计量.

Text 3 England's problematic vocational education system has been subjected to wave after wave of reform.Yet improving the quality of technical education has eluded governments of all colours.University technical colleges（UTCs）are only the latest example of a shiny innovation that ran on to the rocks.Seven UTCs have now announced they are closing their doors.UTCs were intendecl to provide quality vocational education,combining technical and academic learning,for young people from the age of 14.Despite the millions the government has invested in them,ihey have on the whole been plagued by poor GCSE results and an inability to attract sufficient numbers of young people.Several attempts to establish quality vocational eclucation from 14 have failed.The issues affecting UTCs provide an opportunity to revisit whether this merits continuing support.We should take it.Barely a year passes without a lament about the low status of vocational qualifications.These often fail to recognise the chicken and egg that holds vocational learning back.Its status will only improve when ii is not seen as the preserve of those who have been failed by the school system.But while its status is low,these are the only young people likely to try something unproven and untested.This dynamic means new institutions often replicate the problems of the old seconclary moderns.Young people who attend UTCs are more likely to be from poor backgrounds,have made poor progress in primary school,and have attended secondary schools rated poorly by Ofsted.They are children who have been failed by the school system.In this day and age,there is no such thing as a career that does not require functional literacy and numeracy.Yet drawing low-achieving children out of mixed-ability schooling at age 14 makes them less likely to get the decent GCSEs in maths and English that are so critical in the eyes of employers.Setting up alternative vocational institutions for 14-year-olds thus risks closing down future vocational options,rather than expanding them.Vocational education is often posited as an alternative for those who are not"academically minded",orten a code for those who have disengaged from school.Yet this is far more likely to be a symptom of poor teaching ancl a lack of adequate support rather than a young person's inability to engage with a broad pre-16 curriculum that includes both academic and applied learning.Selection by academic ability at age 11 is wrong.But so i.s backdoor selection by academic ability at 14.The rlght to experience an engaging curriculum and finish school with adequate levels of literacy and numeracy is best achieved by options at 16 not 14.This wili not solve everything;but it is a better basis for ensuring 16-year-olds have the skills they need to flourish in any job.
We can learn that those who are not"academically minded"____

A.indicate poor teaching in the school system
B.lack the ability to engage with academic learning
C.blame inadequate support for their failure
D.fail to meet national educational standards