Modals

POSSIBILITY PROBABILITY NECESSITY ABILITY

Pres: can , should , must , can could , would , might , must

(theoretical) -------------------------------------------------------------------------------------- may, could, might

(factual) --------------------------------------------------------------------------------------

Past: could have, should have, _________ could may have , must have --------------------------------------------------------------------------------------

Past

Unfulfilled: could have, _________ _________ (could have) might have --------------------------------------------------------------------------------------

PERMISSION OBLIGATION WILLINGNESS SUGGESTION

Pres: can , should , will*, could, may , shall*, might, would, should --------------------------------------------------------------------------------------

Past: could ________ would have ________ --------------------------------------------------------------------------------------

Past

Unfulfilled: could have, should have , (would have) could have, should have --------------------------------------------------------------------------------------

*Traditionally, will was reserved for promises, while shall was used for any other expression of future willingness; however, this distinction has nearly disappeared from the language, with will becoming the popular form for all expressions of future.