I could bike you could bike she could bike we could bike you could bike they could bike
V-ing form
I could be biking you could be biking she could be biking we could be biking you could be biking they could be biking
Perfect
I could have biked you could have biked she 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 she 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 she 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 she 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 she 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 she 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 she bike? could we bike? could you bike? could they bike?
V-ing form
could I be biking? could you be biking? could she be biking? could we be biking? could you be biking? could they be biking?
Perfect
could I have biked? could you have biked? could she 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 she 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 she 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 she 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 she 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 she have been biking? couldn't we have been biking? couldn't you have been biking? couldn't they have been biking?