I could calcify you could calcify she could calcify we could calcify you could calcify they could calcify
V-ing form
I could be calcifying you could be calcifying she could be calcifying we could be calcifying you could be calcifying they could be calcifying
Perfect
I could have calcified you could have calcified she could have calcified we could have calcified you could have calcified they could have calcified
V-ing perfect
I could have been calcifying you could have been calcifying she could have been calcifying we could have been calcifying you could have been calcifying they could have been calcifying
Negation
Simple form
I couldn't calcify you couldn't calcify she couldn't calcify we couldn't calcify you couldn't calcify they couldn't calcify
V-ing form
I couldn't be calcifying you couldn't be calcifying she couldn't be calcifying we couldn't be calcifying you couldn't be calcifying they couldn't be calcifying
Perfect
I couldn't have calcified you couldn't have calcified she couldn't have calcified we couldn't have calcified you couldn't have calcified they couldn't have calcified
V-ing perfect
I couldn't have been calcifying you couldn't have been calcifying she couldn't have been calcifying we couldn't have been calcifying you couldn't have been calcifying they couldn't have been calcifying
Interrogative form
Simple form
could I calcify? could you calcify? could she calcify? could we calcify? could you calcify? could they calcify?
V-ing form
could I be calcifying? could you be calcifying? could she be calcifying? could we be calcifying? could you be calcifying? could they be calcifying?
Perfect
could I have calcified? could you have calcified? could she have calcified? could we have calcified? could you have calcified? could they have calcified?
V-ing perfect
could I have been calcifying? could you have been calcifying? could she have been calcifying? could we have been calcifying? could you have been calcifying? could they have been calcifying?
Interro-negative form
Simple form
couldn't I calcify? couldn't you calcify? couldn't she calcify? couldn't we calcify? couldn't you calcify? couldn't they calcify?
V-ing form
couldn't I be calcifying? couldn't you be calcifying? couldn't she be calcifying? couldn't we be calcifying? couldn't you be calcifying? couldn't they be calcifying?
Perfect
couldn't I have calcified? couldn't you have calcified? couldn't she have calcified? couldn't we have calcified? couldn't you have calcified? couldn't they have calcified?
V-ing perfect
couldn't I have been calcifying? couldn't you have been calcifying? couldn't she have been calcifying? couldn't we have been calcifying? couldn't you have been calcifying? couldn't they have been calcifying?