如图是一个机器零件，其下部是棱长20厘米的正方体，上部是圆柱形的一半．求它的表面积与体积．
口算显身手！= = = = == = = =
计算下面各题．40××608×27×．
用颜色涂出每种图形的．并说一说每种图形的的个数一样多吗？为什么？
请观察并计算下列各题，你发现了什么？×= ×= == ﹣= ﹣=﹣= ﹣=
计算：×30= ×= ×=×33= ×22= 16×=
= 
= 
= 
= 
=
= 
= 
= 
=
×60
．
．并说一说每种图形的
×
= 
×
= 
=
= 
﹣
﹣
= 
﹣
=
×30= 
×
= 
×
=
×33= 
×22= 16×
=
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