原式=1/2×[-2+(-1)³]÷3²-(2/3)³÷(-1又1/3)=1/2×[-2+(-1)]÷9-8/27÷(-4/3)=1/2×(-3)×1/9-8/27×(-3/4)=-1/6+2/9=-3/18+4/18=1/18
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