西要毛子科技大学三XIDIAN UNIVERSITY21EE4114.1E0414-441 1 1 1 1 1 4 4 1 1 4 4 A A A A     =     −   ( ) 1 1 1 1 0 4 1 1 0 4 2 A E E E A A     =     −   1 . 4 = A