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