动物越高等，动物后天学习行为越复杂，这有利于 [ ]
A．动物获得食物
B．动物逃避敌害
C．动物寻找配偶
D．动物适应复杂多变的生活环境
答案：D
主动脉瓣二瓣化患者表现为（）
A．二尖瓣呈“城墙样”改变
B．SAM现象
C．二尖瓣呈“吊床样”改变
D．主动脉瓣开放呈鱼口状
E．主动脉瓣关闭呈田字形
Project work packages are typically decomposed into smaller components called activities to provide a basis for ______, scheduling, executing, and monitoring and controlling the project work．
A．reviewing B．estimating C．auditing D．expecting
