I could glide you could glide she could glide we could glide you could glide they could glide
V-ing form
I could be gliding you could be gliding she could be gliding we could be gliding you could be gliding they could be gliding
Perfect
I could have glided you could have glided she could have glided we could have glided you could have glided they could have glided
V-ing perfect
I could have been gliding you could have been gliding she could have been gliding we could have been gliding you could have been gliding they could have been gliding
Negation
Simple form
I couldn't glide you couldn't glide she couldn't glide we couldn't glide you couldn't glide they couldn't glide
V-ing form
I couldn't be gliding you couldn't be gliding she couldn't be gliding we couldn't be gliding you couldn't be gliding they couldn't be gliding
Perfect
I couldn't have glided you couldn't have glided she couldn't have glided we couldn't have glided you couldn't have glided they couldn't have glided
V-ing perfect
I couldn't have been gliding you couldn't have been gliding she couldn't have been gliding we couldn't have been gliding you couldn't have been gliding they couldn't have been gliding
Interrogative form
Simple form
could I glide? could you glide? could she glide? could we glide? could you glide? could they glide?
V-ing form
could I be gliding? could you be gliding? could she be gliding? could we be gliding? could you be gliding? could they be gliding?
Perfect
could I have glided? could you have glided? could she have glided? could we have glided? could you have glided? could they have glided?
V-ing perfect
could I have been gliding? could you have been gliding? could she have been gliding? could we have been gliding? could you have been gliding? could they have been gliding?
Interro-negative form
Simple form
couldn't I glide? couldn't you glide? couldn't she glide? couldn't we glide? couldn't you glide? couldn't they glide?
V-ing form
couldn't I be gliding? couldn't you be gliding? couldn't she be gliding? couldn't we be gliding? couldn't you be gliding? couldn't they be gliding?
Perfect
couldn't I have glided? couldn't you have glided? couldn't she have glided? couldn't we have glided? couldn't you have glided? couldn't they have glided?
V-ing perfect
couldn't I have been gliding? couldn't you have been gliding? couldn't she have been gliding? couldn't we have been gliding? couldn't you have been gliding? couldn't they have been gliding?