阅读诗歌，回答问题。

                                                                                                            望    岳
                                                                                                              杜甫
                                                                                            岱宗夫如何？齐鲁青末了。
                                                                                            造化钟神秀，阴阳割昏晓。
                                                                                            荡胸生曾云，决眦入归鸟。
                                                                                            会当凌绝顶，一览众山小。

    There is a big zoo in our city. In the zoo you can see many animals. Look! There is a big ____monkey there. Next to the monkey, there are two ____They are from Africa. They like____in the water. Look! That is a panda. It is two years old. It is from Sichuan, China. It ____bamboo and other plants. There is also a tiger in the zoo. ____favourite food is meat.

鲫鱼体表覆盖鳞片，表面有滑滑的粘液，粘液的作用是（  ）