填空。{#blank#}1{#/blank#}+ {#blank#}2{#/blank#} = {#blank#}3{#/blank#}
{#blank#}4{#/blank#}+ {#blank#}5{#/blank#} = {#blank#}6{#/blank#}
{#blank#}7{#/blank#}- {#blank#}8{#/blank#} = {#blank#}9{#/blank#}
{#blank#}10{#/blank#}- {#blank#}11{#/blank#} = {#blank#}12{#/blank#}
![](http://tikupic.21cnjy.com/fa/41/fa41766e2db3ff96d320eddb84b0e948.jpg)