Present Perfect Continuous

Respuesta correcta: A) She has been studying for the exam all morning.

• A) She has been studying for the exam all morning.Correct. 'Has been' plus the -ing form makes the present perfect continuous, and 'all morning' expresses duration.
• B) She is study for the exam all morning.Incorrect. The -ing form is missing and only 'is' appears, which belongs to the present continuous, not to this unit.
• C) She has been study for the exam all morning.Incorrect. After 'has been' the verb takes the -ing form, not the base form 'study'.
• D) She has studied all morning yesterday.Incorrect. 'All morning' with 'yesterday' refers to a finished past and contradicts the continuous idea of an ongoing duration.

Respuesta correcta: C) have been running

• A) have been runingIncorrect. 'Runing' fails to double the consonant, which the short stressed vowel of 'run' requires.
• B) has been runningIncorrect. 'Has' is for the third person singular, and the subject 'they' is plural.
• C) have been runningCorrect. 'Run' becomes 'running' by doubling the -n, and the auxiliary is 'have been' because the subject is plural.
• D) have been ranIncorrect. 'Ran' is the irregular past simple and cannot replace the -ing form in this unit.

Respuesta correcta: B) has been working

• A) has workIncorrect. After 'has' the verb takes the participle 'worked', not the base form 'work' that appears here.
• B) has been workingCorrect. 'Since 2015' marks a starting point in the past and the action continues, which is the typical use of the continuous.
• C) has been workIncorrect. After 'has been' the verb takes the -ing form 'working', and the present continuous does not combine with 'since' either.
• D) is working since 2015Incorrect. The present continuous does not combine with 'since', because 'since' requires a present perfect tense.

Respuesta correcta: D) haven't seen

• A) haven't been seeingIncorrect. The continuous describes an ongoing process, but this sentence reports that the person has not been seen, not that someone is watching them.
• B) didn't seenIncorrect. After 'did' the verb takes the base form, and 'for a week' also calls for the present perfect.
• C) don't seeIncorrect. 'Don't' is present simple and does not combine with 'for a week', which requires the present perfect.
• D) haven't seenCorrect. The present perfect simple 'haven't seen' works with 'for' when it reports a situation rather than a process.

Respuesta correcta: D) The first focuses on the result and the second on the duration of the activity.

• A) The first is for plural subjects and the second for singular subjects.Incorrect. Both tenses work with any subject; the difference has nothing to do with person.
• B) The first is past and the second is present.Incorrect. Both are present perfect; neither of them is past simple.
• C) The first is formal and the second is informal.Incorrect. The difference is one of grammar and emphasis, not register: both are correct in an exam, and neither is more formal than the other.
• D) The first focuses on the result and the second on the duration of the activity.Correct. The present perfect simple focuses on the result, and the continuous on the duration of the action.

Respuesta correcta: B) have been waiting

• A) had been waitingIncorrect. 'Had been' is the past perfect continuous, which places the waiting in a finished past.
• B) have been waitingCorrect. 'Have been waiting' expresses a duration of forty minutes with the action still in progress.
• C) have been waitedIncorrect. The main verb must take the -ing form, and 'waited' is the participle used in the present perfect simple.
• D) are waiting for forty minutesIncorrect. The present continuous does not take 'for' plus a duration, which belongs to the present perfect.

Respuesta correcta: A) has been writing

• A) has been writingCorrect. The -ing form of 'to write' is 'writing', which drops the silent final -e, and 'all semester' indicates an ongoing period.
• B) has been writeingIncorrect. The -ing form does not keep the -e; the correct form drops the silent final -e of 'write'.
• C) has been writtingIncorrect. 'Write' ends in a silent -e, not in -t, so there is no -t to double in the -ing form.
• D) has been wroteIncorrect. 'Wrote' is the irregular past simple and cannot work as an -ing form.

Respuesta correcta: C) How long have you been waiting?

• A) How long are you waiting?Incorrect. 'How long' is not used with the present continuous; a finished duration takes the past simple, as in 'How long did you wait'.
• B) How long you have been waiting?Incorrect. Question word order requires the auxiliary before the subject: 'have' opens the question.
• C) How long have you been waiting?Correct. 'How long' asks for a duration, and 'have you been' plus the -ing form is the structure of the continuous.
• D) How long do you be waiting?Incorrect. 'Do' does not combine with 'to be' plus the -ing form, and the required structure is 'have been'.

Respuesta correcta: C) have been studying

• A) has been studyingIncorrect. 'Has' is for the third person singular, and 'the students' is a plural subject.
• B) are studyingIncorrect. The present continuous does not take the duration expression 'all night' in this construction.
• C) have been studyingCorrect. The subject is plural, so the auxiliary is 'have been', followed by the -ing form 'studying'.
• D) have been studyIncorrect. The main verb after 'have been' must take the -ing form, not the base form.

Respuesta correcta: A) She has been playing the piano since she was five.

• A) She has been playing the piano since she was five.Correct. 'Since' with a starting point in the past, plus the -ing form, makes a natural continuous sentence.
• B) She has been playing the piano since five years.Incorrect. 'Since' does not take an amount of time; for that you use 'for five years'.
• C) She is playing the piano since she was five.Incorrect. The present continuous does not combine with 'since', which requires a present perfect auxiliary.
• D) She had been playing the piano since five years ago.Incorrect. 'Since' does not combine with 'ago', and the past perfect continuous also belongs to a different time context.

Respuesta correcta: D) have been studying

• A) have been studyIncorrect. After 'have been' the verb takes the -ing form 'studying', not the base form 'study'.
• B) have been studiedIncorrect. 'Studied' is the participle used in the present perfect simple, not an -ing form.
• C) am studying for three years agoIncorrect. 'Ago' refers to a finished past, and the present continuous does not take 'for' with a completed duration.
• D) have been studyingCorrect. 'For three years' gives a duration, and the continuous shows that the action is still ongoing in the present.

Respuesta correcta: B) For six years.

• A) I have lived here for six years.Incorrect. It is a possible reply to the question, but 'How long' asks for a duration, not a clause with a main verb.
• B) For six years.Correct. 'How long' is answered with 'for' plus the duration, and the verb is left out of the answer.
• C) Since six years.Incorrect. 'Since' does not take amounts of time, so the answer with 'for' is the only valid one.
• D) Yes, I have.Incorrect. That answer belongs to a yes/no question, whereas 'How long' expects an amount of time.

Respuesta correcta: B) sitting

• A) sitingIncorrect. After a short stressed vowel the final -t must be doubled, because a single -t produces a misspelled word.
• B) sittingCorrect. 'Sit' ends in a short stressed vowel plus -t, and that consonant is doubled before adding -ing.
• C) siteingIncorrect. The -ing form does not turn the consonant into a vowel, nor does it keep a final -e on the base verb.
• D) satIncorrect. 'Sat' is the irregular past simple and has no role in a continuous tense.

Respuesta correcta: D) has been having

• A) has been haveIncorrect. After 'has been' the verb takes the -ing form 'having', not the base form 'have'.
• B) has been havesIncorrect. 'Haves' is a malformed third-person present simple form and does not exist as an -ing form.
• C) has hadIncorrect. 'Has had' is present perfect simple and does not express the duration of the process, which is what 'for months' calls for.
• D) has been havingCorrect. 'Has been having' expresses that the problem has lasted for months and is still continuing in the present.

Respuesta correcta: C) Have

• A) DidIncorrect. 'Did' is the past simple auxiliary and would require the base form 'work' after it.
• B) AreIncorrect. 'Are' belongs to the present continuous, not to the present perfect continuous structure.
• C) HaveCorrect. With 'you' the auxiliary is 'have been', and the main verb takes the -ing form, as in 'working'.
• D) HasIncorrect. 'Has' agrees with he, she or it, and the subject of the question is 'you'.

Respuesta correcta: A) have known

• A) have knownCorrect. 'Have known' is present perfect simple and is the natural form of 'to know' in this sentence.
• B) have been knowingIncorrect. 'To know' is a stative verb and is not normally used in the present perfect continuous.
• C) have been knowIncorrect. After 'have been' the verb takes the -ing form, and 'to know' does not allow that tense anyway.
• D) had been knowingIncorrect. It combines the past perfect continuous with a stative verb that does not allow that tense.

Respuesta correcta: A) has been raining

• A) has been rainingCorrect. 'Since this morning' marks a starting point in the past, and 'has been raining' expresses that it is still raining now.
• B) have been rainingIncorrect. 'Have' goes with I, you, we and they, and the subject 'it' is third person singular.
• C) has been rainedIncorrect. 'To rain' is intransitive, so it does not allow a passive form or a participle after 'been'.
• D) is raining since this morningIncorrect. The present continuous does not combine with 'since', which requires the present perfect continuous.

Respuesta correcta: D) I have been living in San Juan for ten years.

• A) I have lived in San Juan for ten years.This sentence is correct, because 'live' is a stative verb and takes the present perfect simple.
• B) I have been working in San Juan for ten years.This sentence is correct, because 'work' is an activity verb and allows the present perfect continuous.
• C) I have been studying in San Juan for ten years.This sentence is correct, because 'study' is an activity verb and combines well with the duration.
• D) I have been living in San Juan for ten years.Correct. This is the incorrect sentence: 'live' is a stative verb and does not allow the present perfect continuous.

Respuesta correcta: B) haven't read

• A) haven't been readingIncorrect. The continuous would suggest that the reading is still in progress, but the prompt states that it is already finished.
• B) haven't readCorrect. 'Haven't read' is present perfect simple and reports a result, which is what the prompt calls for.
• C) didn't readIncorrect. The second clause already places the action in a finished past, but the negative calls for the present perfect by contrast.
• D) haven't been readIncorrect. 'To read' is active here and does not allow a passive form with 'have been' after the subject.

Respuesta correcta: C) They have been living in Arecibo since 2018.

• A) They have lived in Arecibo for 2018.Incorrect. 'For' requires a duration, not a date, and the stative verb does not allow the continuous either.
• B) They are living in Arecibo since 2018.Incorrect. The present continuous does not combine with 'since', which belongs to the present perfect continuous.
• C) They have been living in Arecibo since 2018.Correct. 'Since' with a specific date and an ongoing process form a natural present perfect continuous sentence.
• D) They have been living in Arecibo since 2018 years.Incorrect. 'Since' cannot take an amount of time followed by 'years'; for a duration, use 'for'.