人教版七年级下册94页,叙述二元一次方程组的定义说,像(?)这样把具有相同未知数的两个二元一次方程组合在一起,就成了二元一次方程组.笔者认为这种说法不严谨,二元一次方程组不一定都是由两个二元一次方程组合在一起组成的.如方程组(?)是二元一次方程组,但它却是由一个二元一次方程和一个一元一次方程组成的. People's Education Publishing House, seventh grade, next page, p. 94, states that the definition of a bivariate equation states that, as in (?), Combining two bivariate equations of the same unknowns together becomes a binary system of equations. Considering that this statement is not rigorous, a binary system of equations is not always composed of two binary linear equations together, such as the system of equations (?) Is a binary system of equations, but it is a binary A one-time equation and a one-time equation.