Speculation

might have existed

Speculation

We use may, might or could + infinitive to talk about speculation.
  • James may be angry.
  • The bus might come soon.
  • The animals could be hiding in the mountains.

We use may, might or could + have + past participle to speculate about the past.

  • She might have arrived late.
  • He may have been ill yesterday.
  • The animals could have become extinct.

Perfect infinitives are formed with (to) have + past participle, and are used in the following ways:

-with a modal verb, such as must, will, would, can't, could, might and may.

  • The message could have arrived yesterday.

-after certain verbs and be + participle/adjective (seem, look, appear, hope, be known, be thought, be said, be happy, be pleased, be sorry ...).

  • A Queensland Tiger is known to have existed.

1. Perfect infinitive forms.

Read this definition of cryptozoology:

"The search for and scientific examination of evidence related to the possible present existence somewhere on Earth of animal species which are not recognised by zoology."

Look at these beginnings of sentences about cryptozoology:

1. Scientists who have studied the issue...
2. It was presumed to have become extinct....

In sentence 1 have is the auxiliary verb in a present perfect verb phrase.
In sentence 2 have is part of a perfect infinitive form.

Look at more of these sentences with have and has. What form do they correspond to?
Choose the correct option.

2. Past possibility.

What other words can you substitute for may in this sentence, so that the meaning is more or less the same?

The sasquatch could be a surviving form of giant apes that may have crossed from Asia to America.

3. Matching.

Match the sentences on the left with the sentences on the right that mean the same.

4. A dialogue.

Complete the dialogue by rewriting B's sentences using the verb in brackets.


For more information about modal verbs see the Grammar Reference.