下列哪项不是肺动脉高压的病因
A．慢性缺氧B．肺血管阻力增加C．肺小动脉痉挛D．血粘度增加E．左心功能不全
参考答案：E
Later, these rocks proved that ___ in the distant past the Antarctic was covered by plants.
A．at one time
B．at a time
C．at times
D．at the same time
注射丙种球蛋白属于
A．自然自动免疫B．自然被动免疫C．人工自动免疫D．人工被动免疫E．被动自动免疫
