can dull
Regular verb: dull - dulled- dulled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can dull
you can dull
she can dull
we can dull
you can dull
they can dull 	I can be dulling
you can be dulling
she can be dulling
we can be dulling
you can be dulling
they can be dulling	I can have dulled
you can have dulled
she can have dulled
we can have dulled
you can have dulled
they can have dulled	I can have been dulling
you can have been dulling
she can have been dulling
we can have been dulling
you can have been dulling
they can have been dulling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot dull
you cannot dull
she cannot dull
we cannot dull
you cannot dull
they cannot dull 	I cannot be dulling
you cannot be dulling
she cannot be dulling
we cannot be dulling
you cannot be dulling
they cannot be dulling	I cannot have dulled
you cannot have dulled
she cannot have dulled
we cannot have dulled
you cannot have dulled
they cannot have dulled	I cannot have been dulling
you cannot have been dulling
she cannot have been dulling
we cannot have been dulling
you cannot have been dulling
they cannot have been dulling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I dull?
can you dull?
can she dull?
can we dull?
can you dull?
can they dull? 	can I be dulling?
can you be dulling?
can she be dulling?
can we be dulling?
can you be dulling?
can they be dulling? 	can I have dulled?
can you have dulled?
can she have dulled?
can we have dulled?
can you have dulled?
can they have dulled? 	can I have been dulling?
can you have been dulling?
can she have been dulling?
can we have been dulling?
can you have been dulling?
can they have been dulling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not dull?
can you not dull?
can she not dull?
can we not dull?
can you not dull?
can they not dull? 	can I not be dulling?
can you not be dulling?
can she not be dulling?
can we not be dulling?
can you not be dulling?
can they not be dulling? 	can I not have dulled?
can you not have dulled?
can she not have dulled?
can we not have dulled?
can you not have dulled?
can they not have dulled? 	can I not have been dulling?
can you not have been dulling?
can she not have been dulling?
can we not have been dulling?
can you not have been dulling?
can they not have been dulling?