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