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