Future Perfect

Respuesta correcta: A) will have been in service

• A) will have been in service'Will have been' is the future perfect, and it treats the twenty years as finished by the future deadline.
• B) is serving'Is serving' is the present continuous, so it describes service that is still going on today.
• C) served'Served' is the simple past, which places the service entirely before the moment of speaking.
• D) has been serving'Has been serving' is the present perfect continuous and looks forward from now, not from next July.

Respuesta correcta: B) By the time the road opens, the bridge will have been finished.

• A) The road will open when the bridge is finished.'When' with a future form marks the two events as coinciding, so neither one comes first.
• B) By the time the road opens, the bridge will have been finished.'Will have been finished' places the completed bridge before the future moment the road opens.
• C) The bridge has already been finished before the road opens.'Has been finished' is the present perfect, and it never projects onto a future reference point.
• D) The bridge will be finished while the road is opening.'While' makes the two actions overlap, and an overlapping action cannot precede the other.

Respuesta correcta: C) She will recall the valley's quiet once she sees the photos.

• A) The valley will be noisy by the time she sees the photos.The sentence calls the valley quiet, so the opposite adjective contradicts the text.
• B) She has already forgotten the valley completely.'Will remember' points at the future, so the memory is still available to her afterwards.
• C) She will recall the valley's quiet once she sees the photos.'Will remember' links a future reaction to a later event, and the valley is described as quiet.
• D) She never visited the valley at all.The sentence recalls the valley from personal experience, which a visit is implied to have supplied.

Respuesta correcta: D) By the end of next season

• A) At the end of the concert'At the end of' marks a moment, not a completed stretch of time measured up to that moment.
• B) Every Tuesday afternoonA habitual schedule like this one is expressed with the simple present or the simple future.
• C) Just yesterday eveningThat expression points at the past, where the future perfect cannot be used at all.
• D) By the end of next season'By' plus a future deadline measures completion up to that point, which is the future perfect's trigger.

Respuesta correcta: A) will have ruined

• A) will have ruined'Will have ruined' is the future perfect, so the damage is treated as finished by the time of arrival.
• B) ruins'Ruins' is the simple future and says the damage happens at some point, not before a deadline.
• C) ruined'Ruined' is the simple past, which places the damage entirely before the moment of speaking.
• D) is ruining'Is ruining' is the present continuous, so the damage is still in progress at the present time.

Respuesta correcta: B) By the time we arrive, the bus will already have left.

• A) By the time we arrive, the bus will already leave.'Will already leave' projects the departure onto a future moment instead of presenting it as finished before the arrival.
• B) By the time we arrive, the bus will already have left.'Will already have left' presents the departure as complete before the future moment of arrival.
• C) By the time we arrived, the bus will already have left.'Arrived' is the simple past, and a future perfect cannot look back from a past reference point.
• D) By the time we will arrive, the bus had already left.'Had' is the past perfect, which expects a past reference point rather than the future 'will arrive'.

Respuesta correcta: C) The filter will be blocked by the time the technician checks it.

• A) The filter will still be clear when the panel is opened.The clause says the filter had already blocked the airflow, so the opposite condition is excluded.
• B) The filter will only block the airflow after the panel is opened.'After' reverses the order, because the blockage is placed earlier than the inspection of the panel.
• C) The filter will be blocked by the time the technician checks it.'Had already blocked' presents the blockage as finished before the future moment of the check.
• D) The technician will never open the panel at all.The sentence explicitly opens the panel, so refusing to inspect it is not what the text says.

Respuesta correcta: D) will have sold

• A) sells'Sells' is the simple present, which states a general fact and marks no completion at any deadline.
• B) sold'Sold' is the simple past and places the sales before now, not before a future closing date.
• C) is selling'Is selling' is the present continuous, so the sales are still in progress at the present moment.
• D) will have sold'Will have sold' is the future perfect and treats the sales as complete before the future closing.

Respuesta correcta: A) will already have finished

• A) will already have finished'Will already have finished' presents the training as complete before the future moment she hears the news.
• B) has already finished'Has already finished' is the present perfect, which links the training to the present rather than to a later moment.
• C) had already finished'Had' is the past perfect, and it needs a past reference point that the future 'receives' cannot supply.
• D) will already finish'Will already finish' projects the end of the training onto a future moment instead of presenting it as completed.

Respuesta correcta: B) By the deadline next month, the repairs will have been finished.

• A) The repairs are finishing by the deadline next month.'Are finishing' is the present continuous and leaves the completion uncertain at the deadline.
• B) By the deadline next month, the repairs will have been finished.'Will have been finished' presents the repairs as complete before the future deadline.
• C) The repairs were finished by the deadline last month.'Were finished' is the past passive and refers to a deadline that has already passed.
• D) The repairs will be finishing before the deadline next month.'Will be finishing' is the future continuous, which describes progress rather than completion.

Respuesta correcta: C) will have graduated

• A) graduatesThe simple future says the action will happen at some point; it does not state that it is finished before the deadline.
• B) has graduatedThe present perfect places the completed action in the past with present relevance, but it does not project it onto a future point.
• C) will have graduatedThe future perfect presents an action as completed before a stated future deadline, which is exactly what 'by next June' requires.
• D) would have graduatedThat structure belongs to the third conditional and requires an unreal past condition, which is absent here.

Respuesta correcta: C) The scholarship will already be awarded by the time she reads the results.

• A) The scholarship will still be undecided when the results are opened.The clause says the scholarship had already been awarded, so the pending condition is ruled out.
• B) The scholarship will be awarded only after the results are opened.'After' reverses the order, because the award is placed earlier than the opening of the results.
• C) The scholarship will already be awarded by the time she reads the results.'Had already been awarded' presents the award as finished before the future moment she reads the results.
• D) My sister will never open the results at all.The sentence says she opens the results, so refusing to look is not what the text predicts.

Respuesta correcta: D) will have warmed up

• A) will warm up'Will warm up' schedules the warm-up for a future moment without stating that it is already complete.
• B) have warmed up'Have warmed up' is the present perfect and looks back from now rather than forward to the start of the race.
• C) are warming up'Are warming up' is the present continuous, so the warm-up is treated as happening right now.
• D) will have warmed up'Will have warmed up' presents the warm-up as finished before the future start of the marathon.

Respuesta correcta: A) will already have checked

• A) will already have checked'Will already have checked' presents the paperwork review as complete before the shipment arrives.
• B) has already checked'Has already checked' is the present perfect, which ties the review to the present instead of a later moment.
• C) had already checked'Had' is the past perfect, and it expects a past reference point rather than the future 'reaches'.
• D) will already check'Will already check' projects the review onto a future moment instead of stating that it is finished by then.

Respuesta correcta: B) By the time the rains arrive, the farmers will have finished the harvest.

• A) The rains arrive when the farmers have finished the harvest.'When' with a present perfect makes the arrival coincide with the end of the harvest, so neither comes first.
• B) By the time the rains arrive, the farmers will have finished the harvest.'Will have finished' presents the harvest as complete before the future arrival of the rains.
• C) The farmers finished the harvest before the rains arrived.Both verbs are in the past, so the sentence reports a past event instead of a future one.
• D) The farmers will finish the harvest while the rains are arriving.'While' makes the two actions overlap, and an overlapping action cannot precede the other.

Respuesta correcta: C) Three years of service will be complete by the time the verdict is announced.

• A) The defendant will serve three years after the verdict is announced.'After' reverses the order, because the sentence places the years served before the announcement.
• B) The defendant has not served any time before the verdict.The clause says three years were already served, so the absence of prior service is contradicted.
• C) Three years of service will be complete by the time the verdict is announced.'Will have already served' presents the three years as finished before the future announcement.
• D) The judge will never announce a verdict at all.The sentence explicitly announces a verdict, so option D contradicts what the text states.

Respuesta correcta: A) had already started

• A) had already startedThe future reference 'arrived' plus 'by the time' requires the past perfect to show the film was finished starting earlier.
• B) has already startedThe present perfect would anchor the starting point to now rather than to a past moment in the past.
• C) was already startingThis mixes a past continuous with an adverb that points to an earlier completed stage, so the time relationship breaks.
• D) was going to startThe structure 'was going to' announces a plan in the past and says nothing about an action already completed.

Respuesta correcta: D) By the end of the trip, they will have visited six countries.

• A) By the end of the trip, they visit six countries.The simple future only schedules the visits; it makes no claim about how many are finished by then.
• B) At the end of the trip, they visited six countries.The simple past places the visits before the moment of speaking, not before a future reference point.
• C) Before the trip, they will visit six countries.Here the future completes the visits before the trip starts, so the completion point falls in the present, not the future.
• D) By the end of the trip, they will have visited six countries.The future perfect presents the visiting as complete with reference to the future endpoint of the trip.

Respuesta correcta: D) By the time the bell rings tomorrow, the class will have finished the quiz.

• A) By the time the bell rings tomorrow, the class had finished the quiz.'Had finished' is the past perfect, and a past tense cannot look forward to a moment in the future.
• B) By the time the bell rings tomorrow, the class is finishing the quiz.'Is finishing' is the present continuous and leaves the work unfinished at the moment the bell rings.
• C) By the time the bell rings tomorrow, the class has finished the quiz.'Has finished' is the present perfect, which links the quiz to the present and not to a future moment.
• D) By the time the bell rings tomorrow, the class will have finished the quiz.'Will have finished' presents the quiz as complete before the future moment the bell rings.

Respuesta correcta: B) By the end of next month

• A) Every Sunday eveningA habitual schedule is expressed with the simple present or the past simple, depending on the time reference.
• B) By the end of next monthA deadline introduced by 'by' is the standard trigger for the future perfect, because it measures completion up to that point.
• C) Right now, at this very momentThat refers to the present, where the present continuous or the present perfect would be used instead.
• D) Yesterday, during the stormThat refers to the past, so a past form is required and the future perfect would be impossible there.