问题
选择题
农业上为了有效地降低有害昆虫的种群密度，常采用在田间施放人工合成的性引诱剂的方法来治理，性引诱剂治理主要是为[ ]
A．改变昆虫性别比例
B．降低昆虫的出生率
C．增加昆虫的死亡率
D．改变昆虫的年龄组成
答案
答案：B
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农业上为了有效地降低有害昆虫的种群密度，常采用在田间施放人工合成的性引诱剂的方法来治理，性引诱剂治理主要是为[ ]
A．改变昆虫性别比例
B．降低昆虫的出生率
C．增加昆虫的死亡率
D．改变昆虫的年龄组成
答案：B
Johnny lived with his parents in a small town in the mountain. One day there was earthquake near the town. Many houses were damaged(损坏的). Everyone thought that there would be earthquake soon. They were worried that the second earthquake would be than the first. “We must send Johnny to a(n) place.” Johnny’s mother said to her husband, “Many of our friends are sending their children to relatives in other towns.” “We’ll send him to my brother, Peter,” Johnny’s father said, “he lives a long way . Johnny will be safe with him.” He telephoned Johnny’s uncle, Peter, and asked him if he would let Johnny with him. “He’s a good boy,” he said, “he won’t give you any .” “All right,” Johnny’s uncle said, “but I hope he is not . I live a very quiet and peaceful life.” “You won’t know Johnny’s in the house,” his father told him. So Johnny, who was five, to live with his uncle. Two days later, Johnny’s parents a telegram(电报) from Peter. It said, “I am returning the child. Please send an earthquake.”
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