
Regular verb: fire - fired - fired
Simple form | V-ing form | 
| I must fire you must fire she must fire we must fire you must fire they must fire  | I must be firing you must be firing she must be firing we must be firing you must be firing they must be firing  | 
Perfect | V-ing perfect | 
| I must have fired you must have fired she must have fired we must have fired you must have fired they must have fired  | I must have been firing you must have been firing she must have been firing we must have been firing you must have been firing they must have been firing  | 
Simple form | V-ing form | 
| I mustn't fire you mustn't fire she mustn't fire we mustn't fire you mustn't fire they mustn't fire  | I mustn't be firing you mustn't be firing she mustn't be firing we mustn't be firing you mustn't be firing they mustn't be firing  | 
Perfect | V-ing perfect | 
| I mustn't have fired you mustn't have fired she mustn't have fired we mustn't have fired you mustn't have fired they mustn't have fired  | I mustn't have been firing you mustn't have been firing she mustn't have been firing we mustn't have been firing you mustn't have been firing they mustn't have been firing  | 
Simple form | V-ing form | 
| must I fire? must you fire? must she fire? must we fire? must you fire? must they fire?  | must I be firing? must you be firing? must she be firing? must we be firing? must you be firing? must they be firing?  | 
Perfect | V-ing perfect | 
| must I have fired? must you have fired? must she have fired? must we have fired? must you have fired? must they have fired?  | must I have been firing? must you have been firing? must she have been firing? must we have been firing? must you have been firing? must they have been firing?  | 
Simple form | V-ing form | 
| mustn't I fire? mustn't you fire? mustn't she fire? mustn't we fire? mustn't you fire? mustn't they fire?  | mustn't I be firing? mustn't you be firing? mustn't she be firing? mustn't we be firing? mustn't you be firing? mustn't they be firing?  | 
Perfect | V-ing perfect | 
| mustn't I have fired? mustn't you have fired? mustn't she have fired? mustn't we have fired? mustn't you have fired? mustn't they have fired?  | mustn't I have been firing? mustn't you have been firing? mustn't she have been firing? mustn't we have been firing? mustn't you have been firing? mustn't they have been firing?  |