She        a piece of chocolate and gave it to the poor little girl.  [ ]

A. broke off      

B. broke out  

C. broke down    

D. broke into

肺源性心脏病肺动脉高压形成的最主要的因素是

A．继发性红细胞增多
B．血液黏稠度增加
C．血容量增加
D．肺部毛细血管微小栓子形成
E．缺氧及二氧化碳潴留引起肺小血管收缩痉挛