缺词填空。

      I have lived in the countryside since I was a child. There were many k   1    of birds there when I

was young. Every morning, lots of sparrows liked singing and j   2     in the trees outside my window,

while the swallows were busy flying out to f    3     food for their babies. Sometimes in the afternoon, I

could even see eagles f    4    in the sky.

     After twenty years, many of them cannot be seen now. I can seldom see the eagles o   5      the

swallows. The n    6     of the sparrows is getting smaller. Only some of t    7     sing in the morning.

     Why do the birds leave here? First I think it is because the environment is becoming worse now.

The birds can't find e    8     food for themselves and their babies. Second I think it is because people

often k    9     them for food.

     Without the birds around, we won't feel happy any more. So we must p   10     them. Why don't we

do something to help today?

阅读下面文字，按要求答题。（6分）

微博传播信息有一个“传播环理论”，即一个高转发帖子的“传播环”大约有四轮，由轴心到外环的传播比大约是：二环5%，三环55 %，四环25%，五环15 %。其中二环为粉丝转发，三环为粉丝们的粉丝转发，四环是粉丝们的粉丝加泛粉丝，五环是随机粉丝。帖子发出后的首轮传播峰值（以转发10000次计）大约是30分钟之内的前10分钟或后10分钟；而第二轮峰值（第三转播环）在发表后的第30分钟到5个小时的区间内。5小时之后，会形成一个小长尾。要想达到“高转”，必须有“大号”（微博名人）参与其中，否则，一般性帖子很难转出3000次以上。如果“大号”在三环上介入转发，也会在四环上发生威力，但属较少情况。“大号”一般分成三类：一是精英类，他们在各自的领域是佼佼者；二是媒体类，掌握各种消息，自成意见领袖；三是草根类，他们常年活跃于互联网，非常出名。无论哪一类，这些“大号”在信息传播中有很大的影响力。

根据上面的文字，简明概括实现微博信息传播最高峰值的几个关键因素。（不超过40字）