单项选择题 心肺复苏按压时，双手交叉重叠于正确位置后，下面说法正确的是 A、肘关节伸直，向前向下按压 B、肘关节伸直，垂直向下按压 C、肘关节不要求伸直，向下按压 D、以上都不对

单项选择题 骨髓涂片中异常幼稚细胞占40%，其细胞化学染色是：POX(-),SB(-),AS-D-NAE(-),α-NBE(+),且不被NaF抑制，下列最佳选择是( )

单项选择题 Which reasoning method is applied in the paragraph below? Even before the Internet was conceived, Plato talked about the evils of anonymity and its effect on human behavior. He said that the ring, which granted its wearer invisibility, would cause even the most just man to behave in an unjust manner and violate the law. This is the same harm that the unaccountability of Internet anonymity allows