题目下列方程组中,是二元一次方程组的是（ ）A.{x2+3y=12x−y=4\left\{\begin{array}{l}{x}^{2}+3y=1\\ 2x-y=4\end{array}\right.{x2+3y=12x−y=4B.{xy=2x+2y=5\left\{\begin{array}{l}xy=2\\ x+2y=5\end{array}\right.{xy=2x+2y=5C.{m+3n=105m−2n=1\left\{\begin{array}{l}m+3n=10\\ 5m-2n=1\end{array}\right.{m+3n=105m−2n=1D.{a−b=6b+c=3\left\{\begin{array}{l}a-b=6\\ b+c=3\end{array}\right.{a−b=6b+c=3知识点：解二元一次方程组——代入消元法章节：方程与不等式 / 二元一次方程组
