What is the Perfect Infinitive?

The perfect infinitive describes an action that was completed before another action or a specific point in time in the past. It shows that one event finished before another event began.

There are two main forms:

• Standard Form: to have + past participle
• With Modals: modal verb + have + past participle (without ‘to’)

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When Do We Use the Perfect Infinitive?

We use the perfect infinitive in several advanced situations to make our sentences more precise. It helps to show a clear sequence of events in the past.

• To report past events or information from other sources.
• To express feelings or reactions about a past situation.
• To speculate, criticize, or express regret about past actions with modal verbs.
• To comment on something that already happened, often with verbs like seem 或 appear.

Perfect Infinitive with Reporting Structures

We often use the perfect infinitive in reporting structures to talk about past events when the information comes from another source, not firsthand knowledge. This is common in news or formal reports.

• It is used with verbs like report, say, think, believe, allege.
• The structure is often Subject + be + past participle (of reporting verb) + to have + past participle.

例如，, The lava is reported to have taken over a year to reach the village. This means people say the lava took a year.

Expressing Feelings About the Past

You can use the perfect infinitive after adjectives to describe emotions or reactions to something that happened in the past. The feeling is present now, but it is caused by a past event.

• Common adjectives include glad, sad, relieved, happy, sorry, disappointed.
• 该结构是 Adjective + to have + past participle.

For instance, Whole communities were forced to leave, saddened to have lost their homes. Here, ‘saddened’ describes their current feeling about a past loss.

Speculating and Criticizing Past Actions with Modals

When you use a modal verb (should, would, could, might) followed by the perfect infinitive, you are usually talking about past possibilities, regrets, or criticisms.

• Should have + past participle: Expresses regret or criticism about a past action.
• Would have + past participle: Expresses a hypothetical past situation or preference.
• Could have + past participle: Expresses a past possibility or missed opportunity.
• Might have + past participle: Expresses past speculation or uncertainty.

Consider They would have preferred to stay in their ancestral homes. This shows what they wished had happened in the past.

Commenting on Past Events with ‘Seem’ and ‘Appear’

The verbs seem 和 appear are often used with the perfect infinitive to comment on something that happened in the past, especially when you are making an observation or inference.

• This structure suggests that you are drawing a conclusion based on evidence.
• 该结构是 seem/appear + to have + past participle.

An example is A dam was built for the purpose of redirecting water back to the lake, which seems to have worked. This implies that based on current observation, the dam was successful in the past.

示例

• The lava is reported to have taken over a year to reach the village.
• They would have preferred to stay in their ancestral homes.
• Whole communities were forced to leave, saddened to have lost their homes.
• A dam was built for the purpose of redirecting water back to the lake, which seems to have worked.
• The people are moving back, too, glad to have lived to see their beloved Aral Sea come back to life.
• The hanging gardens of Babylon are thought to have been built about 3,000 years ago.
• We were relieved to have made it to the end of the trail before sunset.
• Based on the mess in the kitchen, her dinner party appears to have happened after all.
• The residents might not have wanted to move, but they had to go.
• I should have studied more for the exam.

练习

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西班牙语母语者常犯的错误

Common Mistakes with the Perfect Infinitive

Spanish speakers sometimes make mistakes with the perfect infinitive due to direct translation or confusion with other past tenses.

• Using the simple infinitive instead of the perfect infinitive:
  错误： I am happy to pass the exam yesterday.
  正确： I am happy to have passed the exam yesterday. (The passing happened before the happiness.)
• Confusing with the present perfect: The perfect infinitive is part of a larger structure, not a standalone tense.
  错误： It is reported has taken a year.
  正确： It is reported to have taken a year.
• Incorrect modal structure: Forgetting ‘have’ or ‘to’ with modals.
  错误： They would prefer to stay. (If referring to a past preference that didn’t happen)
  正确： They would have preferred to stay.

常见问题

What is the basic form of the perfect infinitive?

The basic form of the perfect infinitive is to have + past participle. 例如，, to have finished 或 to have seen.

How is the perfect infinitive used with modal verbs?

With modal verbs, the perfect infinitive takes the form modal verb + have + past participle, without ‘to’. For example, should have gone 或 might have known.

Why do we use the perfect infinitive instead of a simple past tense?

We use the perfect infinitive to show that an action was completed BEFORE another action or a specific point in the past. It clarifies the sequence of events, adding a C1 level of precision that simple past tenses might not convey.

Can the perfect infinitive be used in passive voice?

Yes, the perfect infinitive can be used in the passive voice. The form is to have been + past participle. 例如，, The ancient city is believed to have been built by a lost civilization.

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