0.47×0.5×0.80.47×（0.5×0.8）0.47×0.40.188
0.47X0.5Ⅹ0.8=0.47X（0.5X0.8）=0.47X0.4=0.188
先把0.5✘0.8
o.47×（0.5×0.8）＝0.47×0.4＝0.188
