按木箱有盖来算为:1.5×0.8×2+1.5×0.5×2+0.8×0.5×2=2.4+1.5+0.8=4.7(平方米)
(1.5✘0.8+1.5✘0.5+0.8✘0.5)X2=(1.2+0.75+0.4)X2=4.7
