Complex modal forms

May / might / could + have + past participle

We can use may/might/could + be + present participle and may/might/could + have + past participle, with a future time reference, to express our belief that something will happen in the future. Examples:

• Tom’s flight was cancelled, so he may / might / could be arriving later than we expected.
• The murderer may / might / could have left the city by the time we get to the crime scene.

May / might / could + have been + present participle

We can use may / might / could + have been + present participle to refer to situations or activities that were possibly happening at a particular time in the past.

• Do you think she might have been expecting visitors?

Would / will + have + past participle

We use would have + past participle to speak about an imaginary situation in the past.

• Witnesses would have seen them from the street below

If we want to express our belief that a past situation actually happened, we use will have + past participle

• If the thieves smashed a window to get in, people living in the vicinity will certainly have heard something

We can use would have been able to to speak about a possible ability in the past

• Do you think they would have been able to jump from the block across the road?

Should / Ought to + have + past participle

We can use should / ought to + have + past participle to refer to something that didn’t happen in the past, especially if we want to imply some sort of regret or criticism.

• Surely he is aware that he ought to have called the police as soon as he found the door open
• We should have been told about the birthday party well in advance.

Must / can’t / couldn’t + have + past participle

We use can’t have + past participle or couldn’t have + past participle when we want to draw a conclusion about a past event, saying that it was not possible

• One man alone couldn’t have carried all that equipment

On the other hand, if we want to draw a conclusion about something happening at a particular past time, saying that it was possible or certain, we can use must have been + present participle

• The guide must have been waiting at the airport

Must have (had) to

We can use must have to when we want to express a conclusion based on what we know about a present situation.

• He must have to know the password, too

We can use must have had to to conclude something about a past situation

• The robbers must have had to bring a van around to the front of the bank entrance

Must be + present participle

We can use must be + present participle to draw a conclusion about something happening more or less at the time of speaking. We can use must be + present participle or must be going to draw a conclusion about something which will possibly happen in the future.

• I’ll talk to the director of the museum later. She must be feeling quite distressed now.
• The policemen are talking to the bank manager at the moment. They must be going to arrest him.

Had better

We can use had better instead of should / ought to, especially in spoken English, to say that we think it is a good idea (or not) to do something in particular:

• We’d better find out all we can about our new colleague as soon as we can
• We’d better not go in until the forensic team has completed the analysis

We use should or ought to when we talk about the past or make general comments

• I should / ought to have phoned my parents earlier

People living around here should / ought to support the police officers more

Now try the following exercises:

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