a b 互为 相反数,c d 互为倒数,
则,a+b=0 a/b=-1 b/a=-1 cd =1
a 分之b 的绝对值+b 分之a的绝对值+(a +cd+b -2)
=I-1I+I-1I+(0+1-2)
=2+1-2=1