题目下列各式中,去括号或添括号正确的是（ ）A.a2−(2a−b+c)=a2−2a−b+ca^{2}-\left(2a-b+c\right)=a^{2}-2a-b+ca2−(2a−b+c)=a2−2a−b+cB.a−3x+2y−1=a+(−3x+2y−1)a-3x+2y-1=a+\left(-3x+2y-1\right)a−3x+2y−1=a+(−3x+2y−1)C.3x−[5x−(2x−1)]=3x−5x−2x+13x-\left[5x-\left(2x-1\right)\right]=3x-5x-2x+13x−[5x−(2x−1)]=3x−5x−2x+1D.−2x−y−a+1=−(2x−y)+(a−1)-2x-y-a+1=-\left(2x-y\right)+\left(a-1\right)−2x−y−a+1=−(2x−y)+(a−1)知识点：去括号与添括号章节：数与式 / 代数式
