题干

三叶草是牛的主要饲料,三叶草传粉受精靠土蜂,土蜂的天敌是田鼠,田鼠不仅喜食土蜂的蜜和幼虫,而且常常捣毁土蜂的蜂巢。土蜂的多少直接影响三叶草的传粉结籽。猫是田鼠的天敌。下列叙述不正确的是(    )

A:三叶草属于第一营养级

B:田鼠摄入量的10%-20%流入猫体内

C:可用样方法估测土蜂种群数量的逐年变化

D:田鼠等消费者的存在可加快生态系统的物质循环

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答案(点此获取答案解析)

B

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完形填空
   It was on such a cold morning, near Oxford Maryland.    1   I looked out of the window, I found the night’s snow had painted a completely white world. Suddenly a large Canada goose came into my sight. It was standing very still with   2 wings folded to its sides. Its feet were frozen to the ice of the river and it couldn’t move.
   Then from the dark sky, I saw a line of swans moving freely. When they noticed the goose, they landed on the ice as   3   as possible. As the 4  came close to the goose, I was          
    5  that those great swan bills might hurt the goose’s body.
    Amazingly instead, those bills began to  6 on the ice. It went on for  7  an hour. In the end, the goose was free. The swans rose again, and circled in the sky, waiting to see the   8  of their work.
   However, the goose was still standing on the ice and   9 fly because of some ice held in its feathers. Then four of the swans watching in the sky came down to help it move the     10  
away. Luckily, the goose was    11  and could move again.
  When the goose spread its wings to their fullest, the four swans flew up into the sky and joined the circling group. They went on their journey to their secret land. Behind them, the goose was flying with joy. It  12 them and joined the last end of the line.
    I    13them until they disappeared over the tips of the farthest trees. Only then did I realize that tears were running  14 my face. The swans were so warm-hearted that they        15the goose.
    This is a true story. I always think of it in the bad moments, and tell myself, “If so for birds, why not for man?”