刘大爷家的菜园是一个半圆形，直径30米．菜园的面积是多少平方米？如果用竹篱笆把菜园围起来，竹篱笆长多少米？
你能直接写出下列各题的结果吗？试试看×=÷=××= 4.5%=×12=÷4= （+）×== %
计算．×÷÷××÷6×÷7÷．
直接写得数．= 24÷======
直接写出得数． 12×=÷= 0÷=﹣= 12×（×）=×=÷= 20÷=+=×90×=
直接写出得数：×12= 1÷=×=+=÷2= 6﹣= 0÷=×=÷=﹣=
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= 24÷
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﹣
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= 20÷
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×90×
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×12= 1÷
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