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