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