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