could treble
Regular verb: treble - trebled- trebled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could treble
you could treble
she could treble
we could treble
you could treble
they could treble 	I could be trebling
you could be trebling
she could be trebling
we could be trebling
you could be trebling
they could be trebling	I could have trebled
you could have trebled
she could have trebled
we could have trebled
you could have trebled
they could have trebled	I could have been trebling
you could have been trebling
she could have been trebling
we could have been trebling
you could have been trebling
they could have been trebling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't treble
you couldn't treble
she couldn't treble
we couldn't treble
you couldn't treble
they couldn't treble 	I couldn't be trebling
you couldn't be trebling
she couldn't be trebling
we couldn't be trebling
you couldn't be trebling
they couldn't be trebling	I couldn't have trebled
you couldn't have trebled
she couldn't have trebled
we couldn't have trebled
you couldn't have trebled
they couldn't have trebled	I couldn't have been trebling
you couldn't have been trebling
she couldn't have been trebling
we couldn't have been trebling
you couldn't have been trebling
they couldn't have been trebling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I treble?
could you treble?
could she treble?
could we treble?
could you treble?
could they treble? 	could I be trebling?
could you be trebling?
could she be trebling?
could we be trebling?
could you be trebling?
could they be trebling? 	could I have trebled?
could you have trebled?
could she have trebled?
could we have trebled?
could you have trebled?
could they have trebled? 	could I have been trebling?
could you have been trebling?
could she have been trebling?
could we have been trebling?
could you have been trebling?
could they have been trebling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I treble?
couldn't you treble?
couldn't she treble?
couldn't we treble?
couldn't you treble?
couldn't they treble? 	couldn't I be trebling?
couldn't you be trebling?
couldn't she be trebling?
couldn't we be trebling?
couldn't you be trebling?
couldn't they be trebling? 	couldn't I have trebled?
couldn't you have trebled?
couldn't she have trebled?
couldn't we have trebled?
couldn't you have trebled?
couldn't they have trebled? 	couldn't I have been trebling?
couldn't you have been trebling?
couldn't she have been trebling?
couldn't we have been trebling?
couldn't you have been trebling?
couldn't they have been trebling?