I could tie you could tie she could tie we could tie you could tie they could tie
V-ing form
I could be tying you could be tying she could be tying we could be tying you could be tying they could be tying
Perfect
I could have tied you could have tied she 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 she 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 she 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 she 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 she 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 she 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 she tie? could we tie? could you tie? could they tie?
V-ing form
could I be tying? could you be tying? could she be tying? could we be tying? could you be tying? could they be tying?
Perfect
could I have tied? could you have tied? could she 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 she 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 she 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 she 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 she 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 she have been tying? couldn't we have been tying? couldn't you have been tying? couldn't they have been tying?