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