I could lactate you could lactate he could lactate we could lactate you could lactate they could lactate
V-ing form
I could be lactating you could be lactating he could be lactating we could be lactating you could be lactating they could be lactating
Perfect
I could have lactated you could have lactated he could have lactated we could have lactated you could have lactated they could have lactated
V-ing perfect
I could have been lactating you could have been lactating he could have been lactating we could have been lactating you could have been lactating they could have been lactating
Negation
Simple form
I could not lactate you could not lactate he could not lactate we could not lactate you could not lactate they could not lactate
V-ing form
I could not be lactating you could not be lactating he could not be lactating we could not be lactating you could not be lactating they could not be lactating
Perfect
I could not have lactated you could not have lactated he could not have lactated we could not have lactated you could not have lactated they could not have lactated
V-ing perfect
I could not have been lactating you could not have been lactating he could not have been lactating we could not have been lactating you could not have been lactating they could not have been lactating
Interrogative form
Simple form
could I lactate? could you lactate? could he lactate? could we lactate? could you lactate? could they lactate?
V-ing form
could I be lactating? could you be lactating? could he be lactating? could we be lactating? could you be lactating? could they be lactating?
Perfect
could I have lactated? could you have lactated? could he have lactated? could we have lactated? could you have lactated? could they have lactated?
V-ing perfect
could I have been lactating? could you have been lactating? could he have been lactating? could we have been lactating? could you have been lactating? could they have been lactating?
Interro-negative form
Simple form
could I not lactate? could you not lactate? could he not lactate? could we not lactate? could you not lactate? could they not lactate?
V-ing form
could I not be lactating? could you not be lactating? could he not be lactating? could we not be lactating? could you not be lactating? could they not be lactating?
Perfect
could I not have lactated? could you not have lactated? could he not have lactated? could we not have lactated? could you not have lactated? could they not have lactated?
V-ing perfect
could I not have been lactating? could you not have been lactating? could he not have been lactating? could we not have been lactating? could you not have been lactating? could they not have been lactating?