I.           Fill in the blank with a suitable word       People began to keep animals in zoos over 3,000 years (1) …………………, when the rules of China opened an enormous zoo called the Gardens of Intelligence. In many of early zoos, animals were taught (2) ………………… perform for the visitors, but (3) ………………… no longer happens and it is accepted that the purpose of the zoos is to enable (4) …………………  to see animals behaving naturally. Today most cities have a zoo or wildlife park. However, not (5) ………………… approves of zoos. People who think that zoos are a good idea say they provide (6) ………………… with the opportunity (7) ………………… learn about the natural world and be close to wild animals. (8) ………………… of these would not be possible without zoos. On the (9) ………………… hand, some people disapprove (10) ………………… zoos because they believe it is wrong to put animals in cages (11) ………………… argue that in zoos which (12) ………………… managed properly, animals live in dirty conditions and eat unsuitable food.