8B Unit 1 Past and Present Grammar 1. To master the structure and basic usage of present perfect tense(PPT). （掌握现在完成时的基本结构、用法。）2. To learn the rules of forming the past participle of verbs.（学习动词的过去分词变化规则。）3. To learn some time expressions usually used in PPT.（学习常用在现在完成时里的时间表达方式。）Learning aims1. How long has Mr. Chen lived in Sunshine Town?2. Can Mr. Chen see his old friends as often as before?He has lived here since he was born.No. Because most of his old friends have moved away.Lead-in Ask and answer have + done( 动词过去分词 )I've just eaten it.You've changed.We have lived here since then.Have you seen my food ？Have you ever moved house?Has the town changed a lot over the years?······Pre-task: More examplesTry to find more sentences with "have/ has+ done" in the book. When do we use present perfect tense?While-taskTask1: Learn by yourselvesWe use the present perfect tense to talk about an action that started in the past and continues to the present. 表示过去开始，现在还在继续的动作。 We use the present perfect tense to talk about an action that happened in the past and has a connection with the present.表示过去发生的或已完成的动作对现在造成的影响或结果。PastpresentEddie has eaten my food. Eddie ate the food and now Hobo has nothing to eat.We also use the present perfect tense to talk about how many times an action has happened till now.谈论动作已经发生了很多次。I have already read this book many times.We use the simple past tense to talk about what happened at a definite time in the past.（一般过去时谈论在过去的特定时间发生的事）Discuss: What's the basic structure of PPT?Subject ( 主语 )have / has + (not)（助动词）past participle( 过去分词 ) I/You/We/The...
