题目二元一次方程组{2020x-2021y=2019,2019x-2018y=2020.\left\{\begin{matrix}2020x\text{-}2021y\text{=}2019\text{,}\\ 2019x\text{-}2018y\text{=}2020\text{.}\\\end{matrix}\right.{2020x-2021y=2019,2019x-2018y=2020.的解为()(\quad)()A.{x=1,y=2.\left\{\begin{matrix}x\text{=}1\text{,}\\ y\text{=}2\text{.}\\\end{matrix}\right.{x=1,y=2.B.{x=2,y=1.\left\{\begin{matrix}x\text{=}2\text{,}\\ y\text{=}1\text{.}\\\end{matrix}\right.{x=2,y=1.C.{x=2,y=-1.\left\{\begin{matrix}x\text{=}2\text{,}\\ y\text{=-}1\text{.}\\\end{matrix}\right.{x=2,y=-1.D. {x=-1,y=2.\ \left\{\begin{matrix}x\text{=-}1\text{,}\\ y\text{=}2\text{.}\\\end{matrix}\right. {x=-1,y=2.知识点：解二元一次方程组——加减消元法章节：方程与不等式 / 二元一次方程组
