Ax=b有无穷多个解?R(A)=R(B)<n?R(A)<n?Ax=0有非零解.对(A):如 x1+x2=0 x1+2x2=0 x1+x2=0 仅有零解,但 x1+x2=0 x1+2x2=0 x1+x2=1 无解.对(B):如 x1+x2=0 2x1+2x2=0 有非零解,但 x1+x2=0 2x1+2x2=2 无解.对(C):Ax=b有无穷多个解,则Ax=0有非零解,故选择:D.