(1)(+2)-(-3)=(+2)+ ; (2)0-(-4)=0+ ;(3)(-6)-3=(-6)+; (4)1-(+39)=1+ .
若m,n为正数,则根据运算性质填空:
①.
②若d(3)=0.48,则d(9)= , d(0.3)=.