Regular verb: stack - stacked - stacked
Simple form | V-ing form |
I must stack you must stack he must stack we must stack you must stack they must stack | I must be stacking you must be stacking he must be stacking we must be stacking you must be stacking they must be stacking |
Perfect | V-ing perfect |
I must have stacked you must have stacked he must have stacked we must have stacked you must have stacked they must have stacked | I must have been stacking you must have been stacking he must have been stacking we must have been stacking you must have been stacking they must have been stacking |
Simple form | V-ing form |
I mustn't stack you mustn't stack he mustn't stack we mustn't stack you mustn't stack they mustn't stack | I mustn't be stacking you mustn't be stacking he mustn't be stacking we mustn't be stacking you mustn't be stacking they mustn't be stacking |
Perfect | V-ing perfect |
I mustn't have stacked you mustn't have stacked he mustn't have stacked we mustn't have stacked you mustn't have stacked they mustn't have stacked | I mustn't have been stacking you mustn't have been stacking he mustn't have been stacking we mustn't have been stacking you mustn't have been stacking they mustn't have been stacking |
Simple form | V-ing form |
must I stack? must you stack? must he stack? must we stack? must you stack? must they stack? | must I be stacking? must you be stacking? must he be stacking? must we be stacking? must you be stacking? must they be stacking? |
Perfect | V-ing perfect |
must I have stacked? must you have stacked? must he have stacked? must we have stacked? must you have stacked? must they have stacked? | must I have been stacking? must you have been stacking? must he have been stacking? must we have been stacking? must you have been stacking? must they have been stacking? |
Simple form | V-ing form |
mustn't I stack? mustn't you stack? mustn't he stack? mustn't we stack? mustn't you stack? mustn't they stack? | mustn't I be stacking? mustn't you be stacking? mustn't he be stacking? mustn't we be stacking? mustn't you be stacking? mustn't they be stacking? |
Perfect | V-ing perfect |
mustn't I have stacked? mustn't you have stacked? mustn't he have stacked? mustn't we have stacked? mustn't you have stacked? mustn't they have stacked? | mustn't I have been stacking? mustn't you have been stacking? mustn't he have been stacking? mustn't we have been stacking? mustn't you have been stacking? mustn't they have been stacking? |