错因:
改正:
1.5×1= 910÷70= 2.2﹣1.9= 6÷7= 435+199=
+= -= ÷= 20×= ×=
① × = ②24× = ③3× = ④1﹣ =
⑤ ÷2= ⑥2÷ = ⑦ ÷ = ⑧0÷ =
36× = 12× = × = ×3=
1÷ = ÷6= ÷ = 100÷10%=