when i have finished it.疑问这是是什么时态?

when i have finished it.疑问这是是什么时态? when I am finished会错吗?为什么是am ,不是have? 对于when I finished与when I have finished,用法有什么区别,或者说注意什么比如when I——this book,I'm going to sleep.为什么答案是have finished,finished不行吗？ You shall borrow the book when I have finished reading it为什么要用have finished,这里是有什么语法呢,finished不可以吗 I'll go to sleep when I have finished my work.对吗 I have finished my homework.When _____you_____it?为什么填didi,finish?用一般过去式不是要用finished吗? I'll help you when I ___ my work.2.I'll help you when I my work.A.finished B.will finish C.will have finished D.have finished I have just finished it I( )playing tennis when Tom and George arrived括号内该填A.had finished B.have finished C.finish D.finished哪个呢?不管怎样， I will go to see you when you finish/finished/have finished the course是哪个,为什么如果这里只给你finish/finished呢？是选一个 I have finished my work.When ( ) you ( ) it?Tow hours ago. -I have finished my homework.-When ( )you( )it?-Two hours ago 求解析I wonder ______they have finished their homework.I wonder ______they have finished their homework.A that B when C where D if —May I go to the movies tonight,mum?—You can when you______your homeworkA.will finish B.are finishing C.will have finished D.have finished i have finished可否省略have When I ------- my work tomorrow,I will go swimming with you.A.will finish B.have finished C.am finishing D.finished I will write a preface when I have finished the book.和 I will write a preface when I finish the book 的区别, -- When _____ you _____ your homework?--I had finished it befor he_____ back.A.have;finished;came B.have;finished;was comingC.did;finish;came C.did finish;was coming