①竞争必然伤害友谊
②竞争和友谊难以兼顾
③在竞争中要坦然接受并欣赏朋友的成就
④在竞争中要做到相互尊重、相互鼓励
A:①②
B:③④
C:①③
D:②④
The doctor did what he could _______ the sick man.
下列有关于仿生错误的是( )