PRÓPOSITO

ESTA PÁGINA HA SIDO CONCEBIDA CON EL FIN DE APOYAR A LOS ASPIRANTES A LA ESCUELA MÉDICO NAVAL DE MÉXICO EN SU PROCESO DE ESTUDIO DEL TEMARIO PARA SU EVALUACIÓN.

BUEN VIENTO Y BUENA MAR ASPIRANTES Y FUTUROS POTROS.

ATTE. LA MADRE DE UNA CADETE

viernes, 7 de diciembre de 2012

PRESENT PERFECT AND PAST PERFECT

THEME ONE

Present Perfect

FORM

[has/have + past participle]
Examples:
  • You have seen that movie many times.
  • Have you seen that movie many times?
  • You have not seen that movie many times.

USE 1 Unspecified Time Before Now

We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.
Examples:
  • I have seen that movie twenty times.
  • I think I have met him once before.
  • There have been many earthquakes in California.
  • People have traveled to the Moon.
  • People have not traveled to Mars.
  • Have you read the book yet?
  • Nobody has ever climbed that mountain.
  • A: Has there ever been a war in the United States?
    B: Yes, there has been a war in the United States.

How Do You Actually Use the Present Perfect?

The concept of "unspecified time" can be very confusing to English learners. It is best to associate Present Perfect with the following topics:

TOPIC 1 Experience

You can use the Present Perfect to describe your experience. It is like saying, "I have the experience of..." You can also use this tense to say that you have never had a certain experience. The Present Perfect is NOT used to describe a specific event.
Examples:
  • I have been to France.
    This sentence means that you have had the experience of being in France. Maybe you have been there once, or several times.
  • I have been to France three times.
    You can add the number of times at the end of the sentence.
  • I have never been to France.
    This sentence means that you have not had the experience of going to France.
  • I think I have seen that movie before.
  • He has never traveled by train.
  • Joan has studied two foreign languages.
  • A: Have you ever met him?
    B: No, I have not met him.

TOPIC 2 Change Over Time

We often use the Present Perfect to talk about change that has happened over a period of time.
Examples:
  • You have grown since the last time I saw you.
  • The government has become more interested in arts education.
  • Japanese has become one of the most popular courses at the university since the Asian studies program was established.
  • My English has really improved since I moved to Australia.

TOPIC 3 Accomplishments

We often use the Present Perfect to list the accomplishments of individuals and humanity. You cannot mention a specific time.
Examples:
  • Man has walked on the Moon.
  • Our son has learned how to read.
  • Doctors have cured many deadly diseases.
  • Scientists have split the atom.

TOPIC 4 An Uncompleted Action You Are Expecting

We often use the Present Perfect to say that an action which we expected has not happened. Using the Present Perfect suggests that we are still waiting for the action to happen.
Examples:
  • James has not finished his homework yet.
  • Susan hasn't mastered Japanese, but she can communicate.
  • Bill has still not arrived.
  • The rain hasn't stopped.

TOPIC 5 Multiple Actions at Different Times

We also use the Present Perfect to talk about several different actions which have occurred in the past at different times. Present Perfect suggests the process is not complete and more actions are possible.
Examples:
  • The army has attacked that city five times.
  • I have had four quizzes and five tests so far this semester.
  • We have had many major problems while working on this project.
  • She has talked to several specialists about her problem, but nobody knows why she is sick.

Time Expressions with Present Perfect

When we use the Present Perfect it means that something has happened at some point in our lives before now. Remember, the exact time the action happened is not important.
Sometimes, we want to limit the time we are looking in for an experience. We can do this with expressions such as: in the last week, in the last year, this week, this month, so far, up to now, etc.
Examples:
  • Have you been to Mexico in the last year?
  • I have seen that movie six times in the last month.
  • They have had three tests in the last week.
  • She graduated from university less than three years ago. She has worked for three different companies so far.
  • My car has broken down three times this week.

NOTICE

"Last year" and "in the last year" are very different in meaning. "Last year" means the year before now, and it is considered a specific time which requires Simple Past. "In the last year" means from 365 days ago until now. It is not considered a specific time, so it requires Present Perfect.
Examples:
  • I went to Mexico last year.
    I went to Mexico in the calendar year before this one.
  • I have been to Mexico in the last year.
    I have been to Mexico at least once at some point between 365 days ago and now.

USE 2 Duration From the Past Until Now (Non-Continuous Verbs)

With Non-Continuous Verbs and non-continuous uses of Mixed Verbs, we use the Present Perfect to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect.
Examples:
  • I have had a cold for two weeks.
  • She has been in England for six months.
  • Mary has loved chocolate since she was a little girl.
Although the above use of Present Perfect is normally limited to Non-Continuous Verbs and non-continuous uses of Mixed Verbs, the words "live," "work," "teach," and "study" are sometimes used in this way even though they are NOT Non-Continuous Verbs.

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
  • You have only seen that movie one time.
  • Have you only seen that movie one time?

ACTIVE / PASSIVE

Examples:
  • Many tourists have visited that castle. Active
  • That castle has been visited by many tourists. Passive

REALIZA ESTOS EJERCICIOS

EXERCISES AND RELATED TOPICS


Present Perfect Continuous

FORM

[has/have + been + present participle]
Examples:
  • You have been waiting here for two hours.
  • Have you been waiting here for two hours?
  • You have not been waiting here for two hours.

USE 1 Duration from the Past Until Now

We use the Present Perfect Continuous to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect Continuous.
Examples:
  • They have been talking for the last hour.
  • She has been working at that company for three years.
  • What have you been doing for the last 30 minutes?
  • James has been teaching at the university since June.
  • We have been waiting here for over two hours!
  • Why has Nancy not been taking her medicine for the last three days?

USE 2 Recently, Lately

You can also use the Present Perfect Continuous WITHOUT a duration such as "for two weeks." Without the duration, the tense has a more general meaning of "lately." We often use the words "lately" or "recently" to emphasize this meaning.
Examples:
  • Recently, I have been feeling really tired.
  • She has been watching too much television lately.
  • Have you been exercising lately?
  • Mary has been feeling a little depressed.
  • Lisa has not been practicing her English.
  • What have you been doing?

IMPORTANT

Remember that the Present Perfect Continuous has the meaning of "lately" or "recently." If you use the Present Perfect Continuous in a question such as "Have you been feeling alright?", it can suggest that the person looks sick or unhealthy. A question such as "Have you been smoking?" can suggest that you smell the smoke on the person. Using this tense in a question suggests you can see, smell, hear or feel the results of the action. It is possible to insult someone by using this tense incorrectly.

REMEMBER Non-Continuous Verbs/ Mixed Verbs

It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Present Perfect Continuous with these verbs, you must use Present Perfect.
Examples:
  • Sam has been having his car for two years. Not Correct
  • Sam has had his car for two years. Correct

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
  • You have only been waiting here for one hour.
  • Have you only been waiting here for one hour?

ACTIVE / PASSIVE

Examples:
  • Recently, John has been doing the work. Active
  • Recently, the work has been being done by John. Passive
NOTE: Present Perfect Continuous is less commonly used in its passive form.

REALIZA ESTOS EJERCICIOS


EXERCISES AND RELATED TOPICS



THEME TWO

Past Perfect

FORM

[had + past participle]
Examples:
  • You had studied English before you moved to New York.
  • Had you studied English before you moved to New York?
  • You had not studied English before you moved to New York.

USE 1 Completed Action Before Something in the Past

The Past Perfect expresses the idea that something occurred before another action in the past. It can also show that something happened before a specific time in the past.
Examples:
  • I had never seen such a beautiful beach before I went to Kauai.
  • I did not have any money because I had lost my wallet.
  • Tony knew Istanbul so well because he had visited the city several times.
  • Had Susan ever studied Thai before she moved to Thailand?
  • She only understood the movie because she had read the book.
  • Kristine had never been to an opera before last night.
  • We were not able to get a hotel room because we had not booked in advance.
  • A: Had you ever visited the U.S. before your trip in 2006?
    B: Yes, I had been to the U.S. once before.

USE 2 Duration Before Something in the Past (Non-Continuous Verbs)

With Non-Continuous Verbs and some non-continuous uses of Mixed Verbs, we use the Past Perfect to show that something started in the past and continued up until another action in the past.
Examples:
  • We had had that car for ten years before it broke down.
  • By the time Alex finished his studies, he had been in London for over eight years.
  • They felt bad about selling the house because they had owned it for more than forty years.
Although the above use of Past Perfect is normally limited to Non-Continuous Verbs and non-continuous uses of Mixed Verbs, the words "live," "work," "teach," and "study" are sometimes used in this way even though they are NOT Non-Continuous Verbs.

IMPORTANT Specific Times with the Past Perfect

Unlike with the Present Perfect, it is possible to use specific time words or phrases with the Past Perfect. Although this is possible, it is usually not necessary.
Example:
  • She had visited her Japanese relatives once in 1993 before she moved in with them in 1996.

MOREOVER

If the Past Perfect action did occur at a specific time, the Simple Past can be used instead of the Past Perfect when "before" or "after" is used in the sentence. The words "before" and "after" actually tell you what happens first, so the Past Perfect is optional. For this reason, both sentences below are correct.
Examples:
  • She had visited her Japanese relatives once in 1993 before she moved in with them in 1996.
  • She visited her Japanese relatives once in 1993 before she moved in with them in 1996.

HOWEVER

If the Past Perfect is not referring to an action at a specific time, Past Perfect is not optional. Compare the examples below. Here Past Perfect is referring to a lack of experience rather than an action at a specific time. For this reason, Simple Past cannot be used.
Examples:
  • She never saw a bear before she moved to Alaska. Not Correct
  • She had never seen a bear before she moved to Alaska. Correct

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
  • You had previously studied English before you moved to New York.
  • Had you previously studied English before you moved to New York?

ACTIVE / PASSIVE

Examples:
  • George had repaired many cars before he received his mechanic's license. Active
  • Many cars had been repaired by George before he received his mechanic's license. Passive

REALIZA LOS SIGUIENTES EJERCICIOS

EXERCISES AND RELATED TOPICS

Past Perfect Continuous

FORM

[had been + present participle]
Examples:
  • You had been waiting there for more than two hours when she finally arrived.
  • Had you been waiting there for more than two hours when she finally arrived?
  • You had not been waiting there for more than two hours when she finally arrived.

USE 1 Duration Before Something in the Past

We use the Past Perfect Continuous to show that something started in the past and continued up until another time in the past. "For five minutes" and "for two weeks" are both durations which can be used with the Past Perfect Continuous. Notice that this is related to the Present Perfect Continuous; however, the duration does not continue until now, it stops before something else in the past.
Examples:
  • They had been talking for over an hour before Tony arrived.
  • She had been working at that company for three years when it went out of business.
  • How long had you been waiting to get on the bus?
  • Mike wanted to sit down because he had been standing all day at work.
  • James had been teaching at the university for more than a year before he left for Asia.
  • A: How long had you been studying Turkish before you moved to Ankara?
    B: I had not been studying Turkish very long.

USE 2 Cause of Something in the Past

Using the Past Perfect Continuous before another action in the past is a good way to show cause and effect.
Examples:
  • Jason was tired because he had been jogging.
  • Sam gained weight because he had been overeating.
  • Betty failed the final test because she had not been attending class.

Past Continuous vs. Past Perfect Continuous

If you do not include a duration such as "for five minutes," "for two weeks" or "since Friday," many English speakers choose to use the Past Continuous rather than the Past Perfect Continuous. Be careful because this can change the meaning of the sentence. Past Continuous emphasizes interrupted actions, whereas Past Perfect Continuous emphasizes a duration of time before something in the past. Study the examples below to understand the difference.
Examples:
  • He was tired because he was exercising so hard.
    This sentence emphasizes that he was tired because he was exercising at that exact moment.
  • He was tired because he had been exercising so hard.
    This sentence emphasizes that he was tired because he had been exercising over a period of time. It is possible that he was still exercising at that moment OR that he had just finished.

REMEMBER Non-Continuous Verbs / Mixed Verbs

It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Past Perfect Continuous with these verbs, you must use Past Perfect.
Examples:
  • The motorcycle had been belonging to George for years before Tina bought it. Not Correct
  • The motorcycle had belonged to George for years before Tina bought it. Correct

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.
Examples:
  • You had only been waiting there for a few minutes when she arrived.
  • Had you only been waiting there for a few minutes when she arrived?

ACTIVE / PASSIVE

Examples:
  • Chef Jones had been preparing the restaurant's fantastic dinners for two years before he moved to Paris. Active
  • The restaurant's fantastic dinners had been being prepared by Chef Jones for two years before he moved to Paris. Passive
NOTE: Passive forms of the Past Perfect Continuous are not common.

REALIZA LOS SIGUIENTES EJERCICIOS

EXERCISES AND RELATED TOPICS


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