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