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