二元一次方程x-2y=1有无数多组解，下列四组值中不是该方程的解的是(     )

A：$\left\{\begin{array}{c}x=0\\ y=-\frac{1}{2}\end{array}\right.$．

B：$\left\{\begin{array}{c}x=-1\\ y=-1\end{array}\right.$．

C：$\left\{\begin{array}{c}x=1\\ y=0\end{array}\right.$．

D：$\left\{\begin{array}{c}x=1\\ y=1\end{array}\right.$．