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