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