王伯伯要为一块长方形的菜地盖上薄膜，这块地的长是40米，宽是长的一半，王伯伯至少要准备多少平方米的薄膜？
直接写出得数×= 1﹣=÷1=÷=×= 2.5×=×= 52×=×÷×= 0÷5×=
直接写得数．= 24÷====﹣==﹣×=
直接写出得数： 3﹣1.2=（0.1）3= 3÷1=×0.4=﹣=×7=+1= 5×÷5×=+×= 21÷3=
直接写得数．×4= 6﹣=÷=×=×=÷=÷=÷=
= 2.5== 1== 1×= 3÷1%==．
×
= 1﹣
=
÷1=
÷
=
×
= 2.5×
=
×
= 52×
=
×
÷
×
= 0÷5×
=
= 24÷
=
=
=
=
﹣
=
=
=
﹣1.2=（0.1）3= 3÷1
=
×0.4=
﹣
=
×7=
+1
= 5×
÷5×
+
×
= 21
÷3=
×4= 6﹣
=
÷
=
×
×
=
÷
=
÷
=
÷
=
= 2.5
=
= 1
=
= 1
×
= 3÷1%=
=．
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