根据下面资料,回答21-30题
Many people may talk about the love of animals. Whether animals have emotions such as joy, love and heartbreak is still a 21 . It is generally thought that animals are just driven by their 22 . However, there is more than one example to suggest that they may display true love. A male goose Ado seemed to be in such a low 23 that he even did not have the desire to defend himself after the death of his mate. It was not until one year later that he 24 himself together and found another mate. A male parrot did not take a fine-feathered young female seriously; instead, he was 25 by an older female in extremely poor condition. 26 , the male gorilla Timmy rejected two female gorillas introduced to him and liked another gorilla Kate with an old age. Geese, swans, mandarin ducks, and coyotes are all symbols of marital faithfulness. Another example is that an otter Tibby was 27 by a man who got around with a walking stick and she showed great 28 for the man. 29 the death of her master, she made a habit of escaping and finding a man with a walking stick. Of course, there are different viewpoints about whether animals really experience emotions similar to human beings. It is still 30 and open to further research.