I could deteriorate you could deteriorate he could deteriorate we could deteriorate you could deteriorate they could deteriorate
V-ing form
I could be deteriorating you could be deteriorating he could be deteriorating we could be deteriorating you could be deteriorating they could be deteriorating
Perfect
I could have deteriorated you could have deteriorated he could have deteriorated we could have deteriorated you could have deteriorated they could have deteriorated
V-ing perfect
I could have been deteriorating you could have been deteriorating he could have been deteriorating we could have been deteriorating you could have been deteriorating they could have been deteriorating
Negation
Simple form
I could not deteriorate you could not deteriorate he could not deteriorate we could not deteriorate you could not deteriorate they could not deteriorate
V-ing form
I could not be deteriorating you could not be deteriorating he could not be deteriorating we could not be deteriorating you could not be deteriorating they could not be deteriorating
Perfect
I could not have deteriorated you could not have deteriorated he could not have deteriorated we could not have deteriorated you could not have deteriorated they could not have deteriorated
V-ing perfect
I could not have been deteriorating you could not have been deteriorating he could not have been deteriorating we could not have been deteriorating you could not have been deteriorating they could not have been deteriorating
Interrogative form
Simple form
could I deteriorate? could you deteriorate? could he deteriorate? could we deteriorate? could you deteriorate? could they deteriorate?
V-ing form
could I be deteriorating? could you be deteriorating? could he be deteriorating? could we be deteriorating? could you be deteriorating? could they be deteriorating?
Perfect
could I have deteriorated? could you have deteriorated? could he have deteriorated? could we have deteriorated? could you have deteriorated? could they have deteriorated?
V-ing perfect
could I have been deteriorating? could you have been deteriorating? could he have been deteriorating? could we have been deteriorating? could you have been deteriorating? could they have been deteriorating?
Interro-negative form
Simple form
could I not deteriorate? could you not deteriorate? could he not deteriorate? could we not deteriorate? could you not deteriorate? could they not deteriorate?
V-ing form
could I not be deteriorating? could you not be deteriorating? could he not be deteriorating? could we not be deteriorating? could you not be deteriorating? could they not be deteriorating?
Perfect
could I not have deteriorated? could you not have deteriorated? could he not have deteriorated? could we not have deteriorated? could you not have deteriorated? could they not have deteriorated?
V-ing perfect
could I not have been deteriorating? could you not have been deteriorating? could he not have been deteriorating? could we not have been deteriorating? could you not have been deteriorating? could they not have been deteriorating?