A .4/11
B .5/12
C .7/15
D .3/16
[试题]2/3,1/2,3/7,7/18,()A.5/9;B.4/11;C.3/13;D.2/5
[主观题]2/3,1/2,3/7,7/18,()A、4/11;B、5/12;C、7/15;D、3/16
[单选题]1/3,1/7,7/9,1/31.19/45,()A . 11/21B . 13/51C . 63/65D . 91/165
[单选题]:2/3,1/2,2/5,1/3,2/7,( )。A.1/4 B.1/6 C.2/11 D.2/9
[单选题]2/3,1/2,2/5,1/3,2/7,( )。A.1/4B.1/6C.2/11D.2/9
[单选题]1/3,4/7,7/11,2/3,13/19,( )A.16/21B.16/23C.18/21D.17/21
[单选题]1/3,4/7,7/11,2/3,13/19,()A.16/21B.16/23C.18/21D.17/21
[单选题]2/3,1/4,2/5,(),2/7,1/16,A.1/5;B.1/17;c.1/22;d.1/9
[单选题]2/3,1/4,2/5,(),2/7,1/16,A.1/5;B.1/17;C.1/22;D.1/9;
[单选题]1/3,1/2,7/10,19/20,( )。A.19/30B.43/40C.77/60D.59/50