could siphon
Regular verb: siphon - siphoned- siphoned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could siphon
you could siphon
she could siphon
we could siphon
you could siphon
they could siphon 	I could be siphoning
you could be siphoning
she could be siphoning
we could be siphoning
you could be siphoning
they could be siphoning	I could have siphoned
you could have siphoned
she could have siphoned
we could have siphoned
you could have siphoned
they could have siphoned	I could have been siphoning
you could have been siphoning
she could have been siphoning
we could have been siphoning
you could have been siphoning
they could have been siphoning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't siphon
you couldn't siphon
she couldn't siphon
we couldn't siphon
you couldn't siphon
they couldn't siphon 	I couldn't be siphoning
you couldn't be siphoning
she couldn't be siphoning
we couldn't be siphoning
you couldn't be siphoning
they couldn't be siphoning	I couldn't have siphoned
you couldn't have siphoned
she couldn't have siphoned
we couldn't have siphoned
you couldn't have siphoned
they couldn't have siphoned	I couldn't have been siphoning
you couldn't have been siphoning
she couldn't have been siphoning
we couldn't have been siphoning
you couldn't have been siphoning
they couldn't have been siphoning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I siphon?
could you siphon?
could she siphon?
could we siphon?
could you siphon?
could they siphon? 	could I be siphoning?
could you be siphoning?
could she be siphoning?
could we be siphoning?
could you be siphoning?
could they be siphoning? 	could I have siphoned?
could you have siphoned?
could she have siphoned?
could we have siphoned?
could you have siphoned?
could they have siphoned? 	could I have been siphoning?
could you have been siphoning?
could she have been siphoning?
could we have been siphoning?
could you have been siphoning?
could they have been siphoning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I siphon?
couldn't you siphon?
couldn't she siphon?
couldn't we siphon?
couldn't you siphon?
couldn't they siphon? 	couldn't I be siphoning?
couldn't you be siphoning?
couldn't she be siphoning?
couldn't we be siphoning?
couldn't you be siphoning?
couldn't they be siphoning? 	couldn't I have siphoned?
couldn't you have siphoned?
couldn't she have siphoned?
couldn't we have siphoned?
couldn't you have siphoned?
couldn't they have siphoned? 	couldn't I have been siphoning?
couldn't you have been siphoning?
couldn't she have been siphoning?
couldn't we have been siphoning?
couldn't you have been siphoning?
couldn't they have been siphoning?