I could liaise you could liaise he could liaise we could liaise you could liaise they could liaise
V-ing form
I could be liaising you could be liaising he could be liaising we could be liaising you could be liaising they could be liaising
Perfect
I could have liaised you could have liaised he could have liaised we could have liaised you could have liaised they could have liaised
V-ing perfect
I could have been liaising you could have been liaising he could have been liaising we could have been liaising you could have been liaising they could have been liaising
Negation
Simple form
I could not liaise you could not liaise he could not liaise we could not liaise you could not liaise they could not liaise
V-ing form
I could not be liaising you could not be liaising he could not be liaising we could not be liaising you could not be liaising they could not be liaising
Perfect
I could not have liaised you could not have liaised he could not have liaised we could not have liaised you could not have liaised they could not have liaised
V-ing perfect
I could not have been liaising you could not have been liaising he could not have been liaising we could not have been liaising you could not have been liaising they could not have been liaising
Interrogative form
Simple form
could I liaise? could you liaise? could he liaise? could we liaise? could you liaise? could they liaise?
V-ing form
could I be liaising? could you be liaising? could he be liaising? could we be liaising? could you be liaising? could they be liaising?
Perfect
could I have liaised? could you have liaised? could he have liaised? could we have liaised? could you have liaised? could they have liaised?
V-ing perfect
could I have been liaising? could you have been liaising? could he have been liaising? could we have been liaising? could you have been liaising? could they have been liaising?
Interro-negative form
Simple form
could I not liaise? could you not liaise? could he not liaise? could we not liaise? could you not liaise? could they not liaise?
V-ing form
could I not be liaising? could you not be liaising? could he not be liaising? could we not be liaising? could you not be liaising? could they not be liaising?
Perfect
could I not have liaised? could you not have liaised? could he not have liaised? could we not have liaised? could you not have liaised? could they not have liaised?
V-ing perfect
could I not have been liaising? could you not have been liaising? could he not have been liaising? could we not have been liaising? could you not have been liaising? could they not have been liaising?