Present Perfect Vs Past Simple

PRESENT PERFECT vs. PAST SIMPLE 1. THE PROBLEM Ana is having a problem with English tenses. She decides to ask a teacher, Bob, if he can help her. Ana: Bob, I have a problem. Can you help me? Bob: Sure. What's the matter? Ana: I don't know when to use "I saw" and "I've seen." I know there's a difference, but I can't figure out what it is. Do you know? Bob: Oh, yes. That's really quite easy. Let me try to explain it. Ana: Great! Bob: OK. Have you studied this before? Ana: Yes, a little. Bob: When did you study it? Ana: Last week. Is that important? Bob: It's very important. My first question was a general one, so I used the Present Perfect, "have you studied?" My second question was more specific, asking you WHEN, so I used the Past Simple, "when did you study?" Ana: So the time is important? Bob: Yes. The time makes all the difference. When you're not interested in when something happened, or if you don't know, you use the Present Perfect. However, if the time is important, or if you know when something happened, use the Past Simple. Ana: Can you give me another example? Bob: Of course. Have you ever driven a bus? Ana: No, I haven't. Bob: Have you ever eaten pizza? Ana: Yes, I have. Bob: When did you last eat pizza? Ana: I ate pizza a few days ago. Bob: Now do you see the difference? Ana: Hmmm. Yes, I think I understand now. Bob: Either you're a very good student or I'm an excellent teacher! Ana: Maybe both…. Bob: Thanks….I think! 2. THE EXPLANATION Bob certainly IS a good teacher! His explanation was very clear. When the time of a past event or action is stated or understood, we use the Past Simple. When the past event or action is more important than the time when it happened, we use the Present Perfect. Look at these examples: a) I've flown a plane. Do you know when? b) Ana has finished her exercise. Do we know when? c) Ivan went to a concert last night. Do we know when? d) My parents bought a new house last year. Do we know when? e) Mike has read this chapter three times. Do we know when? Answers: a) NO b) NO c) YES d) YES e) NO In examples a) and b) the action or event is more important than the time when it happened. In c) and d) the time is important (it must be important because it is stated in the sentence). In e) we only know that it has happened three times, but we don't know exactly when those three times were.

3. THE RULES The Past Simple is used to express a past action or event when the time is either mentioned or understood by both speakers. Usually in conversation, if one speaker has mentioned a past time, the other speaker does not repeat it. For example: Ana: What did you do last night? Ivan: I went to a concert. The present perfect is used to express past actions or events when the time is either not known or is not important. The event or action is the important element in the sentence. a) Bob has visited several countries in Europe. b) Ana has ridden a motorcycle. In both cases the events are more important than the time. NOTE: We do NOT use specific time expressions with the Present Perfect. We cannot say, for example, "I have eaten spaghetti yesterday." 4. PRACTICE Tell the class about things you have done, but DON'T say when you did them. Examples: I've seen "Titanic" seven times. I've written a lot of poems. I've given blood. Now tell the class WHEN you did certain things. Examples: I saw my brother last weekend. I watched TV last night. I studied French when I was in high school. 5. EVER/NEVER Ever and never are used with the Present Perfect. Ever means "at some time in the past," and never means "at no time in the past." Examples: Have you ever eaten snails? I have never broken my arm. Has your mother ever shouted at you? My sister has never read Shakespeare. 6. PRACTICE Ask another student a question with "Have you ever…?" If the answer is "Yes, I have," ask a second question with "When did you…?" Examples: A: Have you ever drunk whisky? B: Yes, I have. A: When did you drink whisky? A: Have you ever flown in a plane? B: Yes, I have. A: When did you fly in a plane? 7. EXERCISE Complete the following sentences using the Present Perfect or the Past Simple. 1. Ana and Bob (eat) __________________________ in the cafeteria many times. 2. When (you, buy) ______________________________________ your new car? 3. I (finish) ____________________________________________ college in 1992. 4. My mother (go) __________________________________ to Paris last summer. 5. (Ana, feed) _____________________________________ her dog this morning? 6. Bob (drink) ________________________________ six cups of coffee yesterday. 7. Mike (never, play) ____________________________________________ soccer. 8. We (see) ___________________________________ a good movie the other day. 9. (Bob, ever, play) _____________________________________________ tennis? 10. (You, do) ___________________________________ your homework last night? That's all for now. Until next time, keep practicing your English!