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