下列哪项是慢性肺心病肺动脉高压形成的机制
A.肺泡毛细血管床减少超过20%B.酸碱平衡失调C.反复肺部感染D.心肌缺氧E.缺氧、高碳酸血症使肺血管收缩痉挛
参考答案:E
The witness was expected to give the police a description of what had happened, but he was too scared to do any help.
A.special
B.particular
C.complex
D.especial
电阻应变式称重传感器的组成和工作原理?