1、< > > = （说一说略） 2、5/6和7/8:5/6=(5×4)/(6×4)=20/24 7/8=(7×3)/(8×3)=21/24 3/7和2/9:3/7=(3×9)/(7×9)=27/63 2/9=(2×7)/(9×7)=14/63 4/9和7/18:4/9(4×2)/(9×2)

1、< > > = （说一说略） 2、5/6和7/8:5/6=(5×4)/(6×4)=20/24 7/8=(7×3)/(8×3)=21/24 3/7和2/9:3/7=(3×9)/(7×9)=27/63 2/9=(2×7)/(9×7)=14/63 4/9和7/18:4/9(4×2)/(9×2)