I could liquefy you could liquefy she could liquefy we could liquefy you could liquefy they could liquefy
V-ing form
I could be liquefying you could be liquefying she could be liquefying we could be liquefying you could be liquefying they could be liquefying
Perfect
I could have liquefied you could have liquefied she 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 she 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 she 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 she 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 she 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 she 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 she liquefy? could we liquefy? could you liquefy? could they liquefy?
V-ing form
could I be liquefying? could you be liquefying? could she be liquefying? could we be liquefying? could you be liquefying? could they be liquefying?
Perfect
could I have liquefied? could you have liquefied? could she 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 she 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 she 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 she 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 she 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 she have been liquefying? couldn't we have been liquefying? couldn't you have been liquefying? couldn't they have been liquefying?