IV Presentation(课堂讲解，学时分配为1学时左右) Step 1.Warm-up Activity List the main vocabulary in the chapter and explain Let the students have a understanding about the main problems discussed in the chapter. Step 2.The students are required to finish reading the whole text before the class and try to understand the major points of the chapter.The students are supposed to underline the difficult words or structures and raise their questions concerning any difficulties their may have in their understanding of the text,the teacher is responsible for helping them resolve the above problems. Discussion organization(twenty minutes) To develop the student's awareness of the species survival strategies and mechanisms,organize a group discussion among students to let them talk about the problems they have encountered in daily life Part V.Assignment: Exercises: 1.Draw a frame diagram to show the life cycles of bracken and Europcan starling 2.List all mechanisms which bracken and European starling have for their survival and distribution. Check the assignment of the students and help them to solve the difficulties in their assignment