题目

A bird went to look for its happiness in a faraway place.It flew and flew when it suddenly saw a little _____________ flower, whose face was full of smile. Not knowing why, the bird asked the little flower, “You’re going to die. Why are you still so_____________?“Because I will achieve my _____________,” said the little flower.“_____________ is your dream?” “To produce sweet fruit.”Then the little bird saw it: happiness is a _____________ in the heart.The bird continued flying and saw a lame（瘸的） duck ___________ a little duck find the way back home. Although it was disa回答下列关于草原生态系统的问题。（1）草原上的植被能防风固沙、保持水土，对于缓解相邻地区的沙尘天气有一定的作用，这体现了生物多样性的________价值。（2）当草原生态系统处于相对稳定时，优势动物种群的年龄结构类型为________，此时决定某种野兔种群密度的主要直接原因是___________________。（3）生态系统在受到外界干扰因素的破坏后，恢复到原状的能力，叫做________稳定性。例如从群落层次上看，人们可以利用___________规律，在不同阶段种植不同植物以改造盐碱化草原，这样就可以使生态系统从受损的退化状态恢复到正常的健康状态，该操作主要是依赖于生态系统的________能力，其基础是________调节。