【单选题】下列关于心电图波形与心肌动作电位关系的描述,正确的是
D.
心电图一个周期等于心房、心室肌细胞动作电位时程之和
【单选题】249 When hitting a solid object such as a ship or an airplane, the radar waves are reflected back
【单选题】When hitting a solid object such as a ship or an airplane, the radar waves are reflected back they came.
【单选题】打电话要注意掌握通话时间,应遵循的原则是