must duck
Regular verb: duck - ducked- ducked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must duck
you must duck
she must duck
we must duck
you must duck
they must duck 	I must be ducking
you must be ducking
she must be ducking
we must be ducking
you must be ducking
they must be ducking	I must have ducked
you must have ducked
she must have ducked
we must have ducked
you must have ducked
they must have ducked	I must have been ducking
you must have been ducking
she must have been ducking
we must have been ducking
you must have been ducking
they must have been ducking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not duck
you must not duck
she must not duck
we must not duck
you must not duck
they must not duck 	I must not be ducking
you must not be ducking
she must not be ducking
we must not be ducking
you must not be ducking
they must not be ducking	I must not have ducked
you must not have ducked
she must not have ducked
we must not have ducked
you must not have ducked
they must not have ducked	I must not have been ducking
you must not have been ducking
she must not have been ducking
we must not have been ducking
you must not have been ducking
they must not have been ducking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I duck?
must you duck?
must she duck?
must we duck?
must you duck?
must they duck? 	must I be ducking?
must you be ducking?
must she be ducking?
must we be ducking?
must you be ducking?
must they be ducking? 	must I have ducked?
must you have ducked?
must she have ducked?
must we have ducked?
must you have ducked?
must they have ducked? 	must I have been ducking?
must you have been ducking?
must she have been ducking?
must we have been ducking?
must you have been ducking?
must they have been ducking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not duck?
must you not duck?
must she not duck?
must we not duck?
must you not duck?
must they not duck? 	must I not be ducking?
must you not be ducking?
must she not be ducking?
must we not be ducking?
must you not be ducking?
must they not be ducking? 	must I not have ducked?
must you not have ducked?
must she not have ducked?
must we not have ducked?
must you not have ducked?
must they not have ducked? 	must I not have been ducking?
must you not have been ducking?
must she not have been ducking?
must we not have been ducking?
must you not have been ducking?
must they not have been ducking?