抢救呼吸和心跳骤停的落水者时,需要采取心肺复苏的措施,为了提高抢救的成功率,心肺复苏措施的正确顺序是①开放气道②人工呼吸③胸外按压( )
A:①→②→③
B:③→②→①
C:②→①→③
D:③→①→②
—Well.________ you hadn't wasted so much time playing online games.
使3x-1有意义的x的取值范围是( )