题目

—Is Mr. Green in the office? —No, he ________ be in the office. Look, the light in the office is off. A. mustn’t                  B. can’t                    C. needn’t                  D. may not 答案：B已知f(1,1)=1,f(m,n)∈N*(m、n∈N*),且对任何m、n∈N*都有:①f(m,n+1)=f(m,n)+2;②f(m+1,n)=2f(m,n).给出以下三个结论:(1)f(1,5)=9;(2)f(5,1)=16;(3)f(5,6)=26.其中正确的个数为(    )A.3            B.2            C.1            D.0