must window
Regular verb: window - windowed- windowed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must window
you must window
she must window
we must window
you must window
they must window 	I must be windowing
you must be windowing
she must be windowing
we must be windowing
you must be windowing
they must be windowing	I must have windowed
you must have windowed
she must have windowed
we must have windowed
you must have windowed
they must have windowed	I must have been windowing
you must have been windowing
she must have been windowing
we must have been windowing
you must have been windowing
they must have been windowing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not window
you must not window
she must not window
we must not window
you must not window
they must not window 	I must not be windowing
you must not be windowing
she must not be windowing
we must not be windowing
you must not be windowing
they must not be windowing	I must not have windowed
you must not have windowed
she must not have windowed
we must not have windowed
you must not have windowed
they must not have windowed	I must not have been windowing
you must not have been windowing
she must not have been windowing
we must not have been windowing
you must not have been windowing
they must not have been windowing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I window?
must you window?
must she window?
must we window?
must you window?
must they window? 	must I be windowing?
must you be windowing?
must she be windowing?
must we be windowing?
must you be windowing?
must they be windowing? 	must I have windowed?
must you have windowed?
must she have windowed?
must we have windowed?
must you have windowed?
must they have windowed? 	must I have been windowing?
must you have been windowing?
must she have been windowing?
must we have been windowing?
must you have been windowing?
must they have been windowing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not window?
must you not window?
must she not window?
must we not window?
must you not window?
must they not window? 	must I not be windowing?
must you not be windowing?
must she not be windowing?
must we not be windowing?
must you not be windowing?
must they not be windowing? 	must I not have windowed?
must you not have windowed?
must she not have windowed?
must we not have windowed?
must you not have windowed?
must they not have windowed? 	must I not have been windowing?
must you not have been windowing?
must she not have been windowing?
must we not have been windowing?
must you not have been windowing?
must they not have been windowing?