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