第5题: [单项选择]血流正向多普勒频移效应导致的因素是() A. 红细胞背离探头运动 B. 红细胞静止不动 C. 红细胞运动方向垂直于声束方向 D. 红细胞以45°朝向声源移动 E. 与红细胞运动方向无关 参考答案:D 答案解析:当0°<θ<90°时,为正值,即血流方向迎着超声探头而来,频率增高,正向频移。
第11题: [单项选择]A. Every student possesses unique potentials and abilities. B. Everyone has to make a difference to a positive earth. C. Communities play a critical role in the children’s growth. D. Communities play a critical role protecting the earth. 参考答案:B 答案解析:[解析] Q: What is the most important thing for the Green Charter Schools Network