I could multiply you could multiply she could multiply we could multiply you could multiply they could multiply
V-ing form
I could be multiplying you could be multiplying she could be multiplying we could be multiplying you could be multiplying they could be multiplying
Perfect
I could have multiplied you could have multiplied she 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 she 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 she 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 she 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 she 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 she 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 she multiply? could we multiply? could you multiply? could they multiply?
V-ing form
could I be multiplying? could you be multiplying? could she be multiplying? could we be multiplying? could you be multiplying? could they be multiplying?
Perfect
could I have multiplied? could you have multiplied? could she 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 she 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 she 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 she 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 she 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 she have been multiplying? couldn't we have been multiplying? couldn't you have been multiplying? couldn't they have been multiplying?