解:(1)原式=÷(﹣)×÷×1 =×(﹣27)××9 =﹣1; (2)原式=2mn|4m2n2﹣3mn2﹣3m2n2﹣mn2| =2mn|m2n2﹣4mn2| 当m2n2﹣4mn2>0时,原式=2mn(m2n2﹣4mn2)=2m3n3﹣8m2n3; 当m2n2﹣4mn2<0时,原式=2mn(4mn2﹣m2n2)=8m2n3﹣2m3n3.
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