could stall
Regular verb: stall - stalled- stalled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could stall
you could stall
she could stall
we could stall
you could stall
they could stall 	I could be stalling
you could be stalling
she could be stalling
we could be stalling
you could be stalling
they could be stalling	I could have stalled
you could have stalled
she could have stalled
we could have stalled
you could have stalled
they could have stalled	I could have been stalling
you could have been stalling
she could have been stalling
we could have been stalling
you could have been stalling
they could have been stalling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't stall
you couldn't stall
she couldn't stall
we couldn't stall
you couldn't stall
they couldn't stall 	I couldn't be stalling
you couldn't be stalling
she couldn't be stalling
we couldn't be stalling
you couldn't be stalling
they couldn't be stalling	I couldn't have stalled
you couldn't have stalled
she couldn't have stalled
we couldn't have stalled
you couldn't have stalled
they couldn't have stalled	I couldn't have been stalling
you couldn't have been stalling
she couldn't have been stalling
we couldn't have been stalling
you couldn't have been stalling
they couldn't have been stalling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I stall?
could you stall?
could she stall?
could we stall?
could you stall?
could they stall? 	could I be stalling?
could you be stalling?
could she be stalling?
could we be stalling?
could you be stalling?
could they be stalling? 	could I have stalled?
could you have stalled?
could she have stalled?
could we have stalled?
could you have stalled?
could they have stalled? 	could I have been stalling?
could you have been stalling?
could she have been stalling?
could we have been stalling?
could you have been stalling?
could they have been stalling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I stall?
couldn't you stall?
couldn't she stall?
couldn't we stall?
couldn't you stall?
couldn't they stall? 	couldn't I be stalling?
couldn't you be stalling?
couldn't she be stalling?
couldn't we be stalling?
couldn't you be stalling?
couldn't they be stalling? 	couldn't I have stalled?
couldn't you have stalled?
couldn't she have stalled?
couldn't we have stalled?
couldn't you have stalled?
couldn't they have stalled? 	couldn't I have been stalling?
couldn't you have been stalling?
couldn't she have been stalling?
couldn't we have been stalling?
couldn't you have been stalling?
couldn't they have been stalling?