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