Passenger pigeons(旅鸽) once flew over much of the United States in unbelievable numbers. Written accounts from the 18th and 19th centuries described flocks(群) so large that they darkened the sky for hours.
It was calculated that when its population reached its highest point，there were more than 3 billion passenger pigeons—a number equal to 24 to 40 per cent of the total bird population in the United States, making it perhaps the most abundant bird in the world. Even as late as 1870 when their numbers had already become smaller, a flock believed to be 1 mile wide and 320 miles (about 515 kilometres) long was seen near Cincinnati.
Sadly, the abundance of passenger pigeons may have been their undoing. Where the birds were most abundant, people believed there was an everlasting supply and killed them by the thousands. Commercial hunters attracted them to small clearings with grain, waited until pigeons had settled to feed, then threw large nets over them, taking hundreds at a time. The birds were shipped to large cities and sold in restaurants.
By the closing decades of the 19th century, the hardwood forests where passenger pigeons nested had been damaged by Americans' need for wood, which scattered(驱散) the flocks and forced the birds to go farther north, where cold temperatures and spring storms contributed to their decline. Soon the great flocks were gone, never to be seen again.
In 1897, the state of Michigan passed a law prohibiting the killing of passenger pigeons, but by then, no sizable flocks had been seen in the state for 10 years. The last confirmed wild pigeon in the United States was shot by a boy in Pike County, Ohio, in 1900. For a time, a few birds survived under human care. The last of them, known affectionately as Martha, died at the Cincinnati Zoological Garden on September 1, 1914.
24. In the 18th and early 19th centuries, passenger pigeons ________.
A. were the biggest bird in the world
B. lived mainly in the south of America
C. did great harm to the natural environment
D. were the largest bird population in the US
25. The underlined word “undoing” probably refers to the pigeons' “________”.
A. escape B. ruin
C. liberation D. evolution
26. What was the main reason for people to kill passenger pigeons?
A. To seek pleasure.
B. To save other birds.
C. To make money.
D. To protect crops.
27. What can we infer about the law passed in Michigan?
A. It was ignored by the public.
B. It was declared too late.
C. It was unfair.
D. It was strict.
【要点综述】 本文叙述了旅鸽逐渐消失的过程。在美国，18世纪和19世纪旅鸽的数量很多。人们认为旅鸽数量多，会有永久的供应，于是杀害了成千上万的旅鸽。而在19世纪末，美国人伐木驱散了旅鸽。1897年密歇根州通过禁止屠杀旅鸽的法律时，在该州已经10年没有见过大的旅鸽群了。最后一只旅鸽于1914年在辛辛那提动物园死去。
24. D 细节理解题。根据第二段中的“…a number equal to 24 to 40 per cent of the total bird population in the United States…”可知选D。
25. B 词义猜测题。根据第三段中的“Where the birds were most abundant, people believed there was an everlasting supply and killed them by the thousands.”可知，人们认为旅鸽数量多，会有永久的供应，于是杀害了成千上万的旅鸽。由此判断undoing的意思是“死亡，毁灭”。故选B。
26. C 推理判断题。根据第三段中的“Commercial hunters attracted them to small clearings with grain, waited until pigeons had settled to feed, then threw large nets over them, taking hundreds at a time. The birds were shipped to large cities and sold in restaurants.”可知，人们杀死旅鸽主要是为了赚钱。故选C。
27. B 推理判断题。根据最后一段中的“In 1897, the state of Michigan passed a law prohibiting the killing of passenger pigeons, but by then, no sizable flocks had been seen in the state for 10 years.”可知，在密歇根州通过禁止屠杀旅鸽的法律时，在该州已经10年没有见过大的旅鸽群了，由此可推断旅鸽的数量已经很少了，因此这项法律通过得太晚了。故选B。
