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