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