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