Modal Verbs of Probability

Listed below are examples and uses of modal verbs of probability. Modal verbs of probability are used to express an opinion of the speaker based on information that the speaker has. Example: He must be at work, it's 10 o'clock. In this case, the speaker is 100 % sure that the person is at work based on the speaker's knowledge that the person in question usually works at during the day.

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Examples	Usage
They must be in Spain by now. She must have done well on the test.	Use 'must' plus the verb when you are 100% (or almost 100%) sure that something is the case.
She might come this evening. David may invite Jesica to the match. Jack might have gone to France.	Use 'might' or 'may' to express an opinion that you think has a good possibility of being true.
Jane could be at work. Peter could have arrived late.	Use 'could' to express a possibilty which is one of many. This form is not as strong as 'might' or 'may'. It is just one of a number of possibilities.
You can't be serious! They can't have worked until late.	Use 'can't' to express an opinion that you are 100% sure is NOT true. Notice that the past form remains 'can't have done'