阅读理解。 As one of nature's top predators (捕食性动物), the tiger is not an animal, that we would ordinarily think of as being a chicken. However, one tiger, which lives in an English zoo, turned out to be more cowardly than his keepers could ever have imagined. Tanvir, a two-year-old Bengal tiger, got stuck at the top of a new 5m-high activity tower in his enclosure, after climbing it for the first time. The branching tower had been designed to provide mental stimulation for Tanvir by testing his ingenuity, but after scaling the exercise structure in just a few seconds, he lost his nerve when it came to coming back down. Tanvir went on to spend nearly two days at the top of the tower trying to pluck up the courage to attempt a descent. A spokesperson for the zoo said chat Tanvir had taken half an hour to come down from a smaller structure only l.5m high previously, and that the taller tower had clearly been too much for him. 'Every time he gets to the edge, he looks out, puts a paw over, and thinks, 'no, I'm not doing it!'' said Samantha Cordrey. In the end Tanvir's hunger got the better of his fear, and after almost 48 hours he made his way down in order to eat. It appears that Tanvir is none the worse for his experience, but it is not known if he will find the guts (勇 气) to go back up his exercise tower again. The whole episode only serves to underline the difficulties faced by zoo staff in creating environments that will stimulate the animals living in enclosed spaces. 'It was made to challenge him but he's a bit of a wimp,' said Tanvir's keeper. 1. From the first paragraph we can learn that ____. A. tigers are often compared with chickens B. tigers have nothing to do with chickens C. tigers sometimes feed on chickens D. tigers are generally not so cowardly 2. Which of the following is true? A. It took Tranvir an hour and a half to come down from the tower. B. The first tower did not have any effect in training the tiger. C. It is uncertain whether Tanvir will go back up the tower once more. D. Tanvir enjoyed his stay on the tower so much that he refused to come down. 3. What's the purpose of the passage? A. To tell us how timid a tiger became in an English zoo. B. To call on us to protect tigers that are being kept in enclosed spaces. C. To emphasize the difficulties of creating suitable environments for enclosed animals. D. To tell readers how to train wild animals, such as tigers. 4. What can be inferred from the passage? A. In fact the tower structure was not difficult for Tanvir. B. Zoo keepers knew the structure was a bit difficult for Tanvir. C. Tanvir was the only tiger that was trained by the zoo keepers. D. All tigers needed training before they were set free from the zoo.