1：a=0.001001 b=-0.01101,则 a补=0.0010010，b补=1.1001100[a+b]补=a补+b补=0.0010010+1.1001100=1.1.001102:a=-101111 b=11101 ,则 a补=11010001，b补=00011101-b补=11100011[a-b]补=a补+[-b补]= 11010001+11100011=10110100 (进位丢弃)
