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