题目int_(0)^(pi)/(2) (sin x - cos x) , dx = ( )A. 0B. eC. 2D. 都不对$\int_{0}^{\frac{\pi}{2}} (\sin x - \cos x) \, dx = (\quad)$A. 0B. eC. 2D. 都不对题目解答答案A. 0