11,17,( ),31,41,47
A. 19;B. 23;C. 27;D. 29;
1,1/2 , 6/11 ,17/29 , 23/38 ,()A.28/45 B.117/191 C.31/47 D.122/199
7 11 13 17 19 31 47 41 ()A.63 B.195 C.55 D.5
11,13,17,19,23,() A.27 B.29 C.31 D.33
1,7,(),31,49,71 A.9 B.11 C.17 D.19
5,7,3,3,11,19,25,()。 A. 25 B. 2 C. 47 D. 17
-1,1,5,11,19,29,() A.30 B.31 C.32 D.41