肺心病发病的主要机制是
A．肺泡毛细血管急性损伤B．支气管肺感染和阻塞C．肺弥散功能障碍D．肺动脉高压E．肺性脑病
参考答案：D
We should talk about the things _____ the children's understanding in a simple way. [ ]
A. over
B. beyond
C. above
D. under
天然生殖激素(内源性生殖激素)的来源。
