I could bobbie you could bobbie he could bobbie we could bobbie you could bobbie they could bobbie
V-ing form
I could be bobbying you could be bobbying he could be bobbying we could be bobbying you could be bobbying they could be bobbying
Perfect
I could have bobbied you could have bobbied he could have bobbied we could have bobbied you could have bobbied they could have bobbied
V-ing perfect
I could have been bobbying you could have been bobbying he could have been bobbying we could have been bobbying you could have been bobbying they could have been bobbying
Negation
Simple form
I couldn't bobbie you couldn't bobbie he couldn't bobbie we couldn't bobbie you couldn't bobbie they couldn't bobbie
V-ing form
I couldn't be bobbying you couldn't be bobbying he couldn't be bobbying we couldn't be bobbying you couldn't be bobbying they couldn't be bobbying
Perfect
I couldn't have bobbied you couldn't have bobbied he couldn't have bobbied we couldn't have bobbied you couldn't have bobbied they couldn't have bobbied
V-ing perfect
I couldn't have been bobbying you couldn't have been bobbying he couldn't have been bobbying we couldn't have been bobbying you couldn't have been bobbying they couldn't have been bobbying
Interrogative form
Simple form
could I bobbie? could you bobbie? could he bobbie? could we bobbie? could you bobbie? could they bobbie?
V-ing form
could I be bobbying? could you be bobbying? could he be bobbying? could we be bobbying? could you be bobbying? could they be bobbying?
Perfect
could I have bobbied? could you have bobbied? could he have bobbied? could we have bobbied? could you have bobbied? could they have bobbied?
V-ing perfect
could I have been bobbying? could you have been bobbying? could he have been bobbying? could we have been bobbying? could you have been bobbying? could they have been bobbying?
Interro-negative form
Simple form
couldn't I bobbie? couldn't you bobbie? couldn't he bobbie? couldn't we bobbie? couldn't you bobbie? couldn't they bobbie?
V-ing form
couldn't I be bobbying? couldn't you be bobbying? couldn't he be bobbying? couldn't we be bobbying? couldn't you be bobbying? couldn't they be bobbying?
Perfect
couldn't I have bobbied? couldn't you have bobbied? couldn't he have bobbied? couldn't we have bobbied? couldn't you have bobbied? couldn't they have bobbied?
V-ing perfect
couldn't I have been bobbying? couldn't you have been bobbying? couldn't he have been bobbying? couldn't we have been bobbying? couldn't you have been bobbying? couldn't they have been bobbying?