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