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