13．Modern man has cleared the forests for farmland and for wood，and has also carelessly burned them．More than that，though，he has also interfered with the invisible bonds between the living things in the forests．There are many examples of this kind of destruction．The harmfulness of man's interference can be seen in what happened many years ago in the forest of the Kaibab plateau（凯亚巴布高原）of northern Arizona．Man tried to improve on the natural web of forest life and destroyed it instead．
The Kaibab had a storybook forest of large-sized pines，Douglas fir，white fir，blue and Engelmann spruce．In 1882a visitor noted，"We，who have wandered through its forests and parks，have come to regard it as the most attractive region which we have the privilege to visit．"This was also the living place of the Rocky Mountain mule deer．Indians hunted there every autumn to gather meat and skins"．The forest also had mountain lions，timber wolves and bobcats that kept the deer from multiplying too rapidly．
Then，in 1906，President Theodore Roosevelt made the Kaibab a national game preserve．Deer hunting was forbidden．Government hunters started killing off the deer's enemies．In 25 years'time，6，250 mountain lions，wolves and bobcats were killed．Before the program，there were about 4，000 deer in the Kaibab，and by 1924，there were about 100，000．
The deer ate every leaf and twig they could reach．But there was not nearly enough food．Hunting of deer was permitted again．This caused a slight decrease in the deer herd，but a far greater loss resulted from starvation and disease．Some 60 percent of the deer herd died in two winters．By 1930the herd had dropped to 20，000 animals．By 1942 it was down to 8，000．
24．The destruction of the environment of the Kaibab resulted fromB．
A．turning the forest into cultivated land
B．interfering with natural cycle of forest life
C．forest fires caused by man's carelessness
D．cutting the trees for building materials
25．Engelmann spruce（Para.2）is most likely the name ofA．
A．a tree
B．an animal
C．a mountain
D．a game
26．The number of the deer in the Kaibab had increased enormously inC years'time．
A.25
B.6
C.18
D.12
27．Years later，large numbers of deer in the Kaibab died mainly because ofC．
A．the cold
B．the organized kill
C．the shortage of food
D．the poor management．
分析 本文通过讲述北亚利桑那的凯亚巴布高原的森林环境是怎样遭到破坏的例子说明人类对自然生态圈的干涉导致环境破坏．
解答 24．B．细节理解题．第一段第二句More than that，though，he has also interfered （干涉） with the invisiblebonds between the living things in the forests．There are many examples of thiskind of destruction．可知由于干涉森林的自然平衡国家为了保护森林成立了Kaibab的保护区；故选B．
25．A．词义猜测题．从第二段中The Kaibab had astorybook forest of large sized pine，Douglas fir，white fir，blue andEngelmann spruce，and连接并列结构，前面所列举的树木的名字，可猜出Engelmann spruce也是一种树；故选A．
26．C．推理判断题．由文中第三段中的叙述 in 1906，President Theodore Roosevelt made the Kaibab a national game preserve．Deerhunting was forbidden及there were about 4，000 deer in the Kaibabby 1924，从而得知1924-1906=18；故选C．
27．C．细节理解题．由第四段第一．二句The deer ateevery leaf and twig they could reach．But there was not nearly enough food．Hunting of deer was permitted again可知27年后，在kaibab鹿大量死亡的主要原因是食物短缺；故选C．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
