下列既体现唯物辩证法对立统一的观点，又体现唯物辩证法发展观点的是 [ ]
A、和而不同
B、唇亡齿寒
C、吐故纳新
D、一把钥匙开一把锁
答案：C
肺大泡术后常规留置胸腔引流管，尖端应放置于下列哪一种位置
A．膈上
B．胸膜顶
C．肺门
D．叶间裂
E．肋膈角
Competition, they believe ________the national character rather than weaken it. [ ]
A. causes
B. leads
C. strengthens
D. widen
