Degrees of certainty: Future Time

Examples:

100% sure: Kay will do well on the test.
(The speaker feels sure.)

90% sure:
She should do well on the test.
She ought to do well on the test.
(The speaker is almost sure.)

Less than 50% sure:
She may do well on the test.
She might do well on the test.
She could do well on the test.
(The speaker is guessing.)

(a) Kay has been studying hard. She should do/ought to do well on the test tomorrow.
(b) I wonder Why Kay hasn't written us. We should have heard/ought to have heard from her last week.

Should/ought to can be used to express expectations about future events.
In (a): The speaker is saying, "Kay will probably do well on the test. I expect her to do well. That is what I think will happen.

The past form of should/ought to is used to mean that the speaker expected something that did not occur.


Cheers!
Naeem