Gerda Manova: I have read that some languages do not have the present perfect, so I can understand why it seems strange to some learners. Teachers usually explain it this way: Something happened in the past and it STILL touches the present. 1. I HAVE LIVED in Los Angeles since the 1940's. a. My parents MOVED (past) our family to L.A. in the 1940's, and my family STILL lives in L.A.. 2. Mona (9 a.m.): Would you like some breakfast? James: No, thanks. I HAVE already EATEN breakfast. a. James ATE (past) breakfast at 8 a.m. It STILL touches the present because it is only 9 a.m. In theory, the time for breakfast lasts until NOON. After noon, James would then use the past tense. Mona: (2 p.m. She sees James eating very fast): Why are you so hungry? James: Because I DID not EAT breakfast today. 3. The Internet HAS CHANGED the world. a. As you know, the Internet STARTED (past) about 20 years ago, and it STILL touches our lives very, very much. That is, it CONTINUES to change the world in many ways.

Here is another helpful URL with the structure broken down into simple parts: I hope it helps! :) http://www.englishclub.com/grammar/verb-tenses_present-perfect_u.htm

Well it seems complicated because you are using TWO verbs, so it looks like a big task, but if we break it down, we can see how it is constructed and maybe make it easier. First things is that the present simple of HAVE is used. I have walked. YOu HAVE walked. She/He/It has walked. So memorize the present simple of have. THat is not so difficult, and since that never changes, you always have the beginning already formed. second half is the past participle of the verb. I have WALK(ED). so if you know the simple past of a verb, and the simple present of have, you combine them in a row and you have present perfect. (I like to think of it as Present Past), because you are combining the present with the past. It is for actions that occured at UNSPECIFIED TIMES IN THE PAST. Sometime between the last christmas and this christmas (since the last time I saw you), you have grown. At some point in that time frame growth has occured. A better example is this. You haven't seen your family in 5 months, and when you do, your mom has dyed her hair red. "Oh you've dyed your hair, since I last saw you."

http://www.englishpage.com/verbpage/presentperfect.html Tenses aren't my strong point at all, but your example is all past tense, you have grown..........last time I saw you...........but I believe you use the present perfect because the TIME is UNSPECIFIED. I highlight those 2 words, because I think they are the key to understanding the present perfect tense. To be honest it "does my head in" too, because as soon as I understand that I can't use specific time, they seem to change what they deem to be specific time. Your statement though is simple (ohhh I hate it when people say that to me when I don't understand something). The person is merely stating facts, since the last time I saw you......you've grown. Which is obvious really if they're under 18 :) It's present perfect because the time "since the last time I saw you" is not a specific time. Do I know all this stuff off by heart? Do I shite.. (= "no I don't").

It's much simpler than you think. Basically, you're using a past event to describe the present. The simple tenses in English only give the action at the time it happens/happened, so past simple cannot be use to describe the present, nor can present simple be connected to the past. When you do need to connect an earlier event to a later time, you need the perfect tense pattern (for the earlier action) to show this.