第15题: [单项选择]经外周静脉的左心造影技术与右心造影的不同点是() A. 微气泡浓度高 B. 微气泡密度大 C. 发射超声频率高 D. 微气泡比红细胞小 E. 造影剂饱和度小 参考答案:D 答案解析:经外周静脉的左心造影技术与右心造影的不同点是微气泡比红细胞小。造影剂微气泡直径要小于红细胞直径(8μm),这样才能通过肺循环回到左心,使左心室和心肌显影。
第19题: [单项选择]But {{U}}ultimately{{/U}} he gave in. A. undoubtedly B. certainly C. finally D. necessarily 参考答案:C 答案解析: ultimately:最后。finally:最后。The food finally arrived at the end of last month 食品终于在上月末运到了。certainly:当然