口算：2﹣1= 1.4﹣= 1÷= ÷1= +=2+0.25= 9.2×0.25×4= 7×1.3+7×6.7= 4﹣（+）= ﹣=
41×20= 310×3=20×23= 440÷4=
21×30= 720÷8= 33×30=32×20= 87×10=
108×29=270×89=862÷45=403÷23=76×278=576÷18=
46+24= 0÷73=42×20= 100÷5=
10×50= 350÷5=52﹣29= 240×2=
= 1.4﹣
= 
+
=
+0.25= 9.2×0.25×4= 7×1.3+7×6.7= 4
﹣（
+
）= 
=
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