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