① {#blank#}1{#/blank#}；

② {#blank#}2{#/blank#}；

③ {#blank#}3{#/blank#}；

④ {#blank#}4{#/blank#}.

2+3=            2-2=            4-2=            2+0=

4-3=            3+2=            2+2=            5-2=

0+3=            5-3=            2-0=            3-2=

5-1=            3+1=            2-1=            2+1=

1＋0＝               20－10＝             8＋8＝                    7＋4＋3＝

14－6＝             6＋6＝                 8＋7＝                    13－5－4＝