Let us think about the two clocks pictured above. They show different hours. Let us say we ask what has happened, trying to explain why the clocks show different times.
Forms as below might address the question,
“What has happened?”
The question is in the grammatical PRESENT, and the target grammatical time of the responses also is the PRESENT.
Let us say both clocks should have a small handle at the back.
38. The handle MAY HAVE broken off.
38a. It MIGHT HAVE broken off.
39a. It COULD HAVE broken off.
We may wonder if a form as “the handle can have broken off” would be possible as well. CHAPTER 9 shows the Modal verb CAN for objective and general contexts.
23. Bald eagles CAN fly above clouds.
A form as CAN HAVE and in a context as particular as here might be awkward, in American. The form MAY HAVE would be natural.
23b. It MAY HAVE been a bald eagle.
Which of the above forms might address a question in the grammatical PAST, as “What happened?”
38. The handle COULD HAVE broken off.
39a. The handle MIGHT HAVE broken off.
This means that forms as 38a and 39a can address both the grammatical PRESENT and the grammatical PAST.
Let us compare some more Modal syntax, PRESENT or PAST.
40. The handle MUST HAVE broken off.
41. You SHOULD HAVE checked on the handle.
42. The handle OUGHT TO HAVE BEEN checked.
43. You NEEDN’T HAVE manipulated the handle.
Well, the verb TO HAVE can be quite a handle itself. Not only in American English, the verb TO HAVE may occur with Modal patterns, the Passive, and the infinitive.
To work out the verb TO HAVE, we may begin visualizing the infinitive and the head time. Our head time is mauve. The infinitive is underlined.
44. I remember to exercise.
If we recall our exercise as something prior, ANTECEDENT, we might say:
44a. I remember to have exercised.
With the verb TO HAVE, our main grammatical time could be the PAST, PRESENT, as well as FUTURE. Let us think about the effect of our exercise on ourselves. The exercise makes us happy.
MAIN GRAMMATICAL TIME: THE PRESENT
I am happy to have exercised;
MAIN GRAMMATICAL TIME: THE FUTURE
I will be happy to have exercised;
MAIN GRAMMATICAL TIME: THE PAST
I was happy to have exercised.
Would the auxiliary HAVE generally make an antecedent reference in time?
If we say we have learned something, we say we began learning some time before speaking about it, that is, the PRESENT.
If we will have learned, or we had learned something, respectively, we begin learning some time before a FUTURE or PAST time.
Whether a thing is fact or theory, the verb TO HAVE brings an antecedent reference to grammatical time, and it does not mean the time is PAST.
Let us recur to our main grammatical time and syntax.
45. Where is the handle? It MAY HAVE broken off.
(Finding the handle is much of an open question.)
Would oranges have handles?
45a. I thought the handle MIGHT HAVE / COULD HAVE broken off.
(Finding the handle was not much of an open question, in the case.)
Let us focus on the Modal form alone.
45b. The handle MIGHT HAVE / COULD HAVE broken off.
Finding the handle
much of an open question.
The Modal form alone does not give enough guidance. We need the main grammatical time or the context, to tell the target grammatical time.
We can venture our time frames. Feel welcome.
9.2. THE MODAL TIME FRAME