I could buzz you could buzz she could buzz we could buzz you could buzz they could buzz
V-ing form
I could be buzzing you could be buzzing she could be buzzing we could be buzzing you could be buzzing they could be buzzing
Perfect
I could have buzzed you could have buzzed she could have buzzed we could have buzzed you could have buzzed they could have buzzed
V-ing perfect
I could have been buzzing you could have been buzzing she could have been buzzing we could have been buzzing you could have been buzzing they could have been buzzing
Negation
Simple form
I could not buzz you could not buzz she could not buzz we could not buzz you could not buzz they could not buzz
V-ing form
I could not be buzzing you could not be buzzing she could not be buzzing we could not be buzzing you could not be buzzing they could not be buzzing
Perfect
I could not have buzzed you could not have buzzed she could not have buzzed we could not have buzzed you could not have buzzed they could not have buzzed
V-ing perfect
I could not have been buzzing you could not have been buzzing she could not have been buzzing we could not have been buzzing you could not have been buzzing they could not have been buzzing
Interrogative form
Simple form
could I buzz? could you buzz? could she buzz? could we buzz? could you buzz? could they buzz?
V-ing form
could I be buzzing? could you be buzzing? could she be buzzing? could we be buzzing? could you be buzzing? could they be buzzing?
Perfect
could I have buzzed? could you have buzzed? could she have buzzed? could we have buzzed? could you have buzzed? could they have buzzed?
V-ing perfect
could I have been buzzing? could you have been buzzing? could she have been buzzing? could we have been buzzing? could you have been buzzing? could they have been buzzing?
Interro-negative form
Simple form
could I not buzz? could you not buzz? could she not buzz? could we not buzz? could you not buzz? could they not buzz?
V-ing form
could I not be buzzing? could you not be buzzing? could she not be buzzing? could we not be buzzing? could you not be buzzing? could they not be buzzing?
Perfect
could I not have buzzed? could you not have buzzed? could she not have buzzed? could we not have buzzed? could you not have buzzed? could they not have buzzed?
V-ing perfect
could I not have been buzzing? could you not have been buzzing? could she not have been buzzing? could we not have been buzzing? could you not have been buzzing? could they not have been buzzing?