1. [单选题]一个“200.16.23.0/20”表示的CIDR地址块，地址数是( )。
A. 220
B. 212
C. 28
D. 224
2. [单选题]Suppose we have the relation schema R(A,B,C,D)with functional dependencies;F{A→B,B→C,C→D,D→A},then R(A,B,C,D)at least is in
A. 1NF
B. 2NF
C. 3NF
D. BCNF
