:16,4,2,2,()。
A.1
B.2
C.3
D.4
2/3,1/4,2/5,(),2/7,1/16, A.1/5;B.1/17;C.1/22; D
:18,3,16,1,17,2,19,()。A.5 B.4 C.3 D.2
(),-1/4,-3/8,-5/16 A.-1 B.-1/2 C.1/2 D.1
1/2,1/2,1/2,7/16,11/32,() A.15/64 B.1/4 C.13/48 D.1/3
2,4,3,(),13/4,27/8,53/16。A.1 B.7/2 C.7/3 D.4