(1) I go to school on foot sometimes .(2) 因为m、n互为相反数所以m + n = 0因为x、y互为倒数所以 xy = 1因为a的绝对值是1所以 a = 1 或 a = -1a²xy + b²(m + n) + a= 1 + 0 + a= a + 1= 0 或 2...