can dull
Regular verb: dull - dulled- dulled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can dull
you can dull
he can dull
we can dull
you can dull
they can dull 	I can be dulling
you can be dulling
he can be dulling
we can be dulling
you can be dulling
they can be dulling	I can have dulled
you can have dulled
he 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
he 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
he cannot dull
we cannot dull
you cannot dull
they cannot dull 	I cannot be dulling
you cannot be dulling
he cannot be dulling
we cannot be dulling
you cannot be dulling
they cannot be dulling	I cannot have dulled
you cannot have dulled
he 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
he 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 he dull?
can we dull?
can you dull?
can they dull? 	can I be dulling?
can you be dulling?
can he be dulling?
can we be dulling?
can you be dulling?
can they be dulling? 	can I have dulled?
can you have dulled?
can he 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 he 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 he 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 he 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 he 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 he not have been dulling?
can we not have been dulling?
can you not have been dulling?
can they not have been dulling?