阅读下面短文，简略回答所提出的问题．

Cao Yuan was born in 1996．As he was a young kid，he liked to learn on his own． He was not afraid of asking difficult questions．He spent two years finishing his middle and high school classes． At the age of 14． he started taking classes at a university． Although Cao is young． he shows maturity（成熟）beyond his age．

When he was 24， he published（发表）two papers in Nature on May 6th． Nature is one of the top science magazines in the world． Many scientists dream of publishing their papers in it． But it is really hard． One has to make a very important discovery．

Cao's papers are about graphene（石墨烯）一the thinnest and strongest in the word． Scientists first discovered it in 2004．

However， Cao found that sometimes graphene can change， It can change between a superconductor（超导体）﹣a material that conducts electricity（导电）， and an（绝缘体）﹣a material that doesn't conduct electricity． With it， scientists can find cheaper and easier ways to use electricity．

Now Cao is a doctoral student studying at MIT． He isn't afraid of failure in his work． "He Just rolled up his sleeves（袖子）and went on working．"

（1）What did Cao Yuan like to do when he was a kid？ 　　

（2）Where did Cao Yuan publish two papers on May 6th？ 　　

（3）Why do many scientists dream of publishing their papers in Nature？ 　　

（4）When did scientists first discover graphene？ 　　

（5）Is Cao Yuan afraid of failure？