[单项选择]Visitors to the zoo usually pity the animals owing to their particular emotional associations (联想). Which animals should be indeed pitied The first type are those clever and 56 developed animals 57 lively intelligence and desire for activity can 58 no outlet behind the bars of the cage. Those animals living in a free state before 59 in the zoo have a strong desire for moving about 60 , but have to mm around repeatedly in their quarters. Owing to this disappointment, foxes and wolves 61 in places which are far too small, are among the most 62 of all zoo animals. Another sad scene, seldom 63 by ordinary zoo visitors, is the 64 flying trials of swans (天鹅) at migration (迁徙) time. These creatures, like most other water birds, are generally made unable to fly by the 65 of cutting off a tip of the wing bone. 66 such swans in the zoo generally seem happy under 67 care and they raise their young without any trouble, at migration time things become 68 . The birds nev
A. private
B. public
C. different
D. similar