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