I could effervesce you could effervesce she could effervesce we could effervesce you could effervesce they could effervesce
V-ing form
I could be effervescing you could be effervescing she could be effervescing we could be effervescing you could be effervescing they could be effervescing
Perfect
I could have effervesced you could have effervesced she could have effervesced we could have effervesced you could have effervesced they could have effervesced
V-ing perfect
I could have been effervescing you could have been effervescing she could have been effervescing we could have been effervescing you could have been effervescing they could have been effervescing
Negation
Simple form
I could not effervesce you could not effervesce she could not effervesce we could not effervesce you could not effervesce they could not effervesce
V-ing form
I could not be effervescing you could not be effervescing she could not be effervescing we could not be effervescing you could not be effervescing they could not be effervescing
Perfect
I could not have effervesced you could not have effervesced she could not have effervesced we could not have effervesced you could not have effervesced they could not have effervesced
V-ing perfect
I could not have been effervescing you could not have been effervescing she could not have been effervescing we could not have been effervescing you could not have been effervescing they could not have been effervescing
Interrogative form
Simple form
could I effervesce? could you effervesce? could she effervesce? could we effervesce? could you effervesce? could they effervesce?
V-ing form
could I be effervescing? could you be effervescing? could she be effervescing? could we be effervescing? could you be effervescing? could they be effervescing?
Perfect
could I have effervesced? could you have effervesced? could she have effervesced? could we have effervesced? could you have effervesced? could they have effervesced?
V-ing perfect
could I have been effervescing? could you have been effervescing? could she have been effervescing? could we have been effervescing? could you have been effervescing? could they have been effervescing?
Interro-negative form
Simple form
could I not effervesce? could you not effervesce? could she not effervesce? could we not effervesce? could you not effervesce? could they not effervesce?
V-ing form
could I not be effervescing? could you not be effervescing? could she not be effervescing? could we not be effervescing? could you not be effervescing? could they not be effervescing?
Perfect
could I not have effervesced? could you not have effervesced? could she not have effervesced? could we not have effervesced? could you not have effervesced? could they not have effervesced?
V-ing perfect
could I not have been effervescing? could you not have been effervescing? could she not have been effervescing? could we not have been effervescing? could you not have been effervescing? could they not have been effervescing?