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