could function
Regular verb: function - functioned- functioned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could function
you could function
he could function
we could function
you could function
they could function 	I could be functioning
you could be functioning
he could be functioning
we could be functioning
you could be functioning
they could be functioning	I could have functioned
you could have functioned
he could have functioned
we could have functioned
you could have functioned
they could have functioned	I could have been functioning
you could have been functioning
he could have been functioning
we could have been functioning
you could have been functioning
they could have been functioning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not function
you could not function
he could not function
we could not function
you could not function
they could not function 	I could not be functioning
you could not be functioning
he could not be functioning
we could not be functioning
you could not be functioning
they could not be functioning	I could not have functioned
you could not have functioned
he could not have functioned
we could not have functioned
you could not have functioned
they could not have functioned	I could not have been functioning
you could not have been functioning
he could not have been functioning
we could not have been functioning
you could not have been functioning
they could not have been functioning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I function?
could you function?
could he function?
could we function?
could you function?
could they function? 	could I be functioning?
could you be functioning?
could he be functioning?
could we be functioning?
could you be functioning?
could they be functioning? 	could I have functioned?
could you have functioned?
could he have functioned?
could we have functioned?
could you have functioned?
could they have functioned? 	could I have been functioning?
could you have been functioning?
could he have been functioning?
could we have been functioning?
could you have been functioning?
could they have been functioning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not function?
could you not function?
could he not function?
could we not function?
could you not function?
could they not function? 	could I not be functioning?
could you not be functioning?
could he not be functioning?
could we not be functioning?
could you not be functioning?
could they not be functioning? 	could I not have functioned?
could you not have functioned?
could he not have functioned?
could we not have functioned?
could you not have functioned?
could they not have functioned? 	could I not have been functioning?
could you not have been functioning?
could he not have been functioning?
could we not have been functioning?
could you not have been functioning?
could they not have been functioning?