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