last friday , we had an lesson and it was really unforgettable because it was the last lesson given by our kind english teacher ,mr tang.

　　when mr tang slowly went into the classroom ,we could see clearly that it was hard for him to leave us though he had taught us for only three months.he said something about him future plan ,which moved us all deeply.then he started the last lesson.

　　we all listened attentively(认真地) to every word he said .if only we had done like this before!(如果我们以前就这样该多好啊)the naughty boys unusually behaved well in this last lesson.

　　it was obvious(明显的)that all of us had the common feeling that we wouldn't let him go.

　　though we didn't want our good teacher to go ,it seemed to be too late . as the saying goes,"only when we lose something do we realize the value of it."(这句你应该能理解)

　　at last,with the bell ringing,mr tang looked at us all soulfully(深情地) and expressed what he thought. he hoped that we would make progress in our study and become good citizens(公民) in society.

　　what an unforgettable lesson!