must invalidate
Regular verb: invalidate - invalidated- invalidated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must invalidate
you must invalidate
she must invalidate
we must invalidate
you must invalidate
they must invalidate 	I must be invalidating
you must be invalidating
she must be invalidating
we must be invalidating
you must be invalidating
they must be invalidating	I must have invalidated
you must have invalidated
she must have invalidated
we must have invalidated
you must have invalidated
they must have invalidated	I must have been invalidating
you must have been invalidating
she must have been invalidating
we must have been invalidating
you must have been invalidating
they must have been invalidating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not invalidate
you must not invalidate
she must not invalidate
we must not invalidate
you must not invalidate
they must not invalidate 	I must not be invalidating
you must not be invalidating
she must not be invalidating
we must not be invalidating
you must not be invalidating
they must not be invalidating	I must not have invalidated
you must not have invalidated
she must not have invalidated
we must not have invalidated
you must not have invalidated
they must not have invalidated	I must not have been invalidating
you must not have been invalidating
she must not have been invalidating
we must not have been invalidating
you must not have been invalidating
they must not have been invalidating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I invalidate?
must you invalidate?
must she invalidate?
must we invalidate?
must you invalidate?
must they invalidate? 	must I be invalidating?
must you be invalidating?
must she be invalidating?
must we be invalidating?
must you be invalidating?
must they be invalidating? 	must I have invalidated?
must you have invalidated?
must she have invalidated?
must we have invalidated?
must you have invalidated?
must they have invalidated? 	must I have been invalidating?
must you have been invalidating?
must she have been invalidating?
must we have been invalidating?
must you have been invalidating?
must they have been invalidating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not invalidate?
must you not invalidate?
must she not invalidate?
must we not invalidate?
must you not invalidate?
must they not invalidate? 	must I not be invalidating?
must you not be invalidating?
must she not be invalidating?
must we not be invalidating?
must you not be invalidating?
must they not be invalidating? 	must I not have invalidated?
must you not have invalidated?
must she not have invalidated?
must we not have invalidated?
must you not have invalidated?
must they not have invalidated? 	must I not have been invalidating?
must you not have been invalidating?
must she not have been invalidating?
must we not have been invalidating?
must you not have been invalidating?
must they not have been invalidating?