could diffuse
Regular verb: diffuse - diffused- diffused

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could diffuse
you could diffuse
he could diffuse
we could diffuse
you could diffuse
they could diffuse 	I could be diffusing
you could be diffusing
he could be diffusing
we could be diffusing
you could be diffusing
they could be diffusing	I could have diffused
you could have diffused
he could have diffused
we could have diffused
you could have diffused
they could have diffused	I could have been diffusing
you could have been diffusing
he could have been diffusing
we could have been diffusing
you could have been diffusing
they could have been diffusing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't diffuse
you couldn't diffuse
he couldn't diffuse
we couldn't diffuse
you couldn't diffuse
they couldn't diffuse 	I couldn't be diffusing
you couldn't be diffusing
he couldn't be diffusing
we couldn't be diffusing
you couldn't be diffusing
they couldn't be diffusing	I couldn't have diffused
you couldn't have diffused
he couldn't have diffused
we couldn't have diffused
you couldn't have diffused
they couldn't have diffused	I couldn't have been diffusing
you couldn't have been diffusing
he couldn't have been diffusing
we couldn't have been diffusing
you couldn't have been diffusing
they couldn't have been diffusing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I diffuse?
could you diffuse?
could he diffuse?
could we diffuse?
could you diffuse?
could they diffuse? 	could I be diffusing?
could you be diffusing?
could he be diffusing?
could we be diffusing?
could you be diffusing?
could they be diffusing? 	could I have diffused?
could you have diffused?
could he have diffused?
could we have diffused?
could you have diffused?
could they have diffused? 	could I have been diffusing?
could you have been diffusing?
could he have been diffusing?
could we have been diffusing?
could you have been diffusing?
could they have been diffusing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I diffuse?
couldn't you diffuse?
couldn't he diffuse?
couldn't we diffuse?
couldn't you diffuse?
couldn't they diffuse? 	couldn't I be diffusing?
couldn't you be diffusing?
couldn't he be diffusing?
couldn't we be diffusing?
couldn't you be diffusing?
couldn't they be diffusing? 	couldn't I have diffused?
couldn't you have diffused?
couldn't he have diffused?
couldn't we have diffused?
couldn't you have diffused?
couldn't they have diffused? 	couldn't I have been diffusing?
couldn't you have been diffusing?
couldn't he have been diffusing?
couldn't we have been diffusing?
couldn't you have been diffusing?
couldn't they have been diffusing?