如图1所示,将一个正四棱锥(底面为正方形,四条测棱相等)的其中四条边剪开,得到图2,则被剪开的四条边有可能是( )
The more you are in English, the better you'll learn it.
要使电阻在单位时间内产生的热量减少一半,则应( )