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