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