题目内容
f(k)+k+1
A.f(k)+1 B.f(k)+k C.f(k)+k+1 D.k·f(k)
A.f(k+1)=f(k)+k+1
B.f(k+1)=f(k)+k-1
C.f(k+1)=f(k)+k
D.f(k+1)=f(k)+k+2