在△ABC中，若a²＋b²－c²<0，则△ABC是

我国河流开发中存在的问题:

任务型阅读根据短文内容，判断正误。
    When I grow up，I'm going to do what l want to do．I'm going to move somewhere interesting．Paris (巴黎)sounds like a city that I could enjoy．There are lots of art exhibitions(艺术展)．I want to be an artist．So how am I going to do it? First，I'm going to find a part-time job for a year or two and save some money．And I'm going to be a student at an art school in Paris．And l want to learn French at the same time．Next，I'm going to hold(举办)art exhibitions because l want to earn some money(挣一些钱)and buy a big house for my parents．I also want to travel all over the world．One day I'm going to retire(退休)somewhere quiet and beautiful．

当m=____ 时，关于x的方程（m﹣2）$x^{m^2-2}$+2x﹣1=0是一元二次方程．

我国历史上第一个国家——夏朝建立于约公元前2070年，这一年属于（  ）