
Regular verb: happen - happened - happened
Simple form | V-ing form | 
| - - it shall happen - - -  | - - it shall be happening - - -  | 
Perfect | V-ing perfect | 
| - - it shall have happened - - -  | - - it shall have been happening - - -  | 
Simple form | V-ing form | 
| - - it shall not happen - - -  | - - it shall not be happening - - -  | 
Perfect | V-ing perfect | 
| - - it shall not have happened - - -  | - - it shall not have been happening - - -  | 
Simple form | V-ing form | 
| - - shall it happen? - - -  | - - shall it be happening? - - -  | 
Perfect | V-ing perfect | 
| - - shall it have happened? - - -  | - - shall it have been happening? - - -  | 
Simple form | V-ing form | 
| - - shall it not happen? - - -  | - - shall it not be happening? - - -  | 
Perfect | V-ing perfect | 
| - - shall it not have happened? - - -  | - - shall it not have been happening? - - -  |