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
Whenever I met her, ______ was fairly often, she greeted me with a sweet smile.
A.who
B.which
C.when
D.that
已知二次函数f(x)=(lga)x2+2x+4lga的最小值为3,求(log5)2+loga2•loga50得值.