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