1）0.75 3/7 7/13 4/53/7 <7/13< 0.75 <4/5 2）0.4 12/13 25/260.4<12/13<25/26 3）2又1/3 2又4/9 2.07 2又5/122.07<2又1/3<2又5/12<2又4/9 4）2/5 0.52/5 <0.5
