An aspect of English that troubles many learners is the correct use of the modal verbs, including must, may, can, should, ought to and might .
The difficulties are of two kinds. Firstly, there is the difficulty of learning which forms of the modal verbs are possible in the various tenses. And secondly, there is the more subtle difficulty of choosing the correct modal to express the meaning that you want to convey. Related to this is the difficulty of comprehending the meaning of the modal verbs you hear or read.
This second problem results from the fact that some of the modal verbs can be used both epistemically and deontically. These terms cover concepts such as likelihood, necessity, permission, obligation and ability.
As a quick example, She must be sick uses must epistemically to express the likelihood that she is sick. On the other hand, She must work late today uses must deontically to express obligation.
Following is a taster to some of the difficulties you will find on the modal verbs pages listed below.
The statement You might have told me, when read rather than heard, is ambiguous. Which two meanings does the sentence have, and how would the sentences be spoken so that the listener would have no difficulty understanding what you meant?
You might have told me can mean either It is possible that you told me (but I don't remember). Or it can mean Why didn't you tell me? For example, You might have told me that she's divorced. I felt such a fool when I asked where her husband was!
With the first meaning, the word might is usually stressed and the rest of the sentence is spoken with falling pitch.
With the second meaning, each of the words in the statement receive equal stress and the pitch remains on the same level.
In fact, there is a way that the meaning could be determined from the written words alone. Of course, the context would usually be enough to know what the writer wants to say, but in addition to this, the sentence having the second meaning would probably end with an exclamation mark. You might have told me!