can sub
Regular verb: sub - subbed- subbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can sub
you can sub
he can sub
we can sub
you can sub
they can sub 	I can be subbing
you can be subbing
he can be subbing
we can be subbing
you can be subbing
they can be subbing	I can have subbed
you can have subbed
he can have subbed
we can have subbed
you can have subbed
they can have subbed	I can have been subbing
you can have been subbing
he can have been subbing
we can have been subbing
you can have been subbing
they can have been subbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot sub
you cannot sub
he cannot sub
we cannot sub
you cannot sub
they cannot sub 	I cannot be subbing
you cannot be subbing
he cannot be subbing
we cannot be subbing
you cannot be subbing
they cannot be subbing	I cannot have subbed
you cannot have subbed
he cannot have subbed
we cannot have subbed
you cannot have subbed
they cannot have subbed	I cannot have been subbing
you cannot have been subbing
he cannot have been subbing
we cannot have been subbing
you cannot have been subbing
they cannot have been subbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I sub?
can you sub?
can he sub?
can we sub?
can you sub?
can they sub? 	can I be subbing?
can you be subbing?
can he be subbing?
can we be subbing?
can you be subbing?
can they be subbing? 	can I have subbed?
can you have subbed?
can he have subbed?
can we have subbed?
can you have subbed?
can they have subbed? 	can I have been subbing?
can you have been subbing?
can he have been subbing?
can we have been subbing?
can you have been subbing?
can they have been subbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not sub?
can you not sub?
can he not sub?
can we not sub?
can you not sub?
can they not sub? 	can I not be subbing?
can you not be subbing?
can he not be subbing?
can we not be subbing?
can you not be subbing?
can they not be subbing? 	can I not have subbed?
can you not have subbed?
can he not have subbed?
can we not have subbed?
can you not have subbed?
can they not have subbed? 	can I not have been subbing?
can you not have been subbing?
can he not have been subbing?
can we not have been subbing?
can you not have been subbing?
can they not have been subbing?