话题导入 As we all know'，animals are humans' best friends.Animals arevaluable resources(资源）that are helpful to us all through ourhistory.However, many kinds of animals are in danger now! Animals havebeen killed for their fur and feathers, for food, for entertainment,orsimply because they are in the way.Thousands of kinds of animals havedisappeared from the earth forever so far.Hundreds more are on the dangerlist today.About 170 kinds in the United States alone are considered indanger.It is high time that we should pay more attention to how to protectthese animals on the earth.