天津外国语大学2020年考研成绩查询与复核相关事项你了解吗？

逆转录的方向是
A.3'—5' B. 5' —3' C. N 端—C 端 D. C 端—N 端

甲、乙、丙、丁是四位天资极高的艺术家,他们分别是舞蹈家、画家、歌唱家和作家,尚不能确定其中每个人所从事的专业领域。已知：①有一天晚上,甲和丙出席歌唱家的首次演出;②画家曾为乙和作家画过肖像;③作家正准备写一本甲的传记,他所写的丁的传记是畅销书;④甲从来没有见过丙;⑤作家和乙是亲戚。下面哪项关于身份的描述是正确的?

A.甲是画家。
B.乙是歌唱家。
C.丙是舞蹈家。
D.丁是作家。
E.甲是作家。

Text 2 You would think that the young and digitally intellectual-the generation that grew up with computers at their fingertips-would be the least likely age group to fall victim of online fiaud.But the opposite is true."We've bought into stereotypes about fraud victims-they're usually seen as wlnerable and elderly,or gullible and poorly educated,"says Emma Fletcher,product manager at the BBB Institute."These stereotypes are strongly held-and they are wrong.We are all at risk,but younger and more educated individuals are actually the most likely to be deceived."Similarly,a 2016 report by Norton,the antivirus company,found that 44 per cent of millennials had been the victim of an online crime in the past year,compared with just 16 per cent ofbaby boomers.Research by Barclays this year backs this up.The Barclays Digital Safety Index highlights that almost two thirds of 18-24 year-olds had fallen prey to hackers or viruses.Yet when asked about actions taken to prevent future attacks,millennials were less likely than their older counterparts to take positive action,such as installing an anti-virus software following a computer system collapse.One reason is what is known as"optimism bias"-the idea that other people might be more One reason is what is known as"optimism bias"-the idea that other people might be more vulnerable than you and that you know better.Younger people are usually more knowledgeable about IT than those in the generations above them.But this makes them less likely to heed advice about staying safe,whereas,perhaps surprisingly,older people are more inclined to listen.But this is not the only reason.Younger people spend far more time online.They shop more there（meaning their card details are entered more ofien and stored in many more databases）and they share much more personal information online.According to Ofcom's 2016 Media Use and Attitudes Report,more than 90 pcr cent of those aged 16-34 have social-media accounts.For those aged between 55 and 64,this figure drops t0 51 per cent.For those 65 and over,it's 30 per cent.Interestingly,though,according the Office ofNational Statistics,older people are more likely to be victims ofrepeat fraud.This may be because they tend to be more trusting.Research at the University of California suggests that this isn't just because they grew up in more innocent times.Rather,age-related changes in the brain mean that as people get older,they tend to trust more and question less.30.Which of the following can be the best title ofthe text?

A.Who Is More Likely to Be Cheated,Young or the Older
B.How to Guard Against Online Scam
C.Millennials:The Most Vulnerable Online Victim
D.The Older Who Trusts More

一个垄断企业面临两个分离的市场。市场1的需求函数为

市场2的需求函数为

垄断厂商生产的边际成本为1，不存在固定成本。 (1)假定垄断厂商可以实施三级价格歧视。求两个市场的利润最大化垄断价格和产量以及垄断厂商的总利润，两个市场的消费者剩余之和，以及总剩余之和。（总剩余定义为总消费者剩余加上总利润） (2)假定垄断厂商不能实施价格歧视而只能在两个市场收取统一的价格。求利润最大化的垄断价格和产量以及垄断厂商的总利润，两个市场的消费者剩余之和，以及总剩余之和。（提示：你需要确定垄断者在两个市场都销售是否是最优的） (3)对于本题中所描述的需求状况，三级价格歧视对社会有益吗？请加以解释。（注意：不能仅仅比较数值大小）