I could concatenate you could concatenate he could concatenate we could concatenate you could concatenate they could concatenate
V-ing form
I could be concatenating you could be concatenating he could be concatenating we could be concatenating you could be concatenating they could be concatenating
Perfect
I could have concatenated you could have concatenated he could have concatenated we could have concatenated you could have concatenated they could have concatenated
V-ing perfect
I could have been concatenating you could have been concatenating he could have been concatenating we could have been concatenating you could have been concatenating they could have been concatenating
Negation
Simple form
I could not concatenate you could not concatenate he could not concatenate we could not concatenate you could not concatenate they could not concatenate
V-ing form
I could not be concatenating you could not be concatenating he could not be concatenating we could not be concatenating you could not be concatenating they could not be concatenating
Perfect
I could not have concatenated you could not have concatenated he could not have concatenated we could not have concatenated you could not have concatenated they could not have concatenated
V-ing perfect
I could not have been concatenating you could not have been concatenating he could not have been concatenating we could not have been concatenating you could not have been concatenating they could not have been concatenating
Interrogative form
Simple form
could I concatenate? could you concatenate? could he concatenate? could we concatenate? could you concatenate? could they concatenate?
V-ing form
could I be concatenating? could you be concatenating? could he be concatenating? could we be concatenating? could you be concatenating? could they be concatenating?
Perfect
could I have concatenated? could you have concatenated? could he have concatenated? could we have concatenated? could you have concatenated? could they have concatenated?
V-ing perfect
could I have been concatenating? could you have been concatenating? could he have been concatenating? could we have been concatenating? could you have been concatenating? could they have been concatenating?
Interro-negative form
Simple form
could I not concatenate? could you not concatenate? could he not concatenate? could we not concatenate? could you not concatenate? could they not concatenate?
V-ing form
could I not be concatenating? could you not be concatenating? could he not be concatenating? could we not be concatenating? could you not be concatenating? could they not be concatenating?
Perfect
could I not have concatenated? could you not have concatenated? could he not have concatenated? could we not have concatenated? could you not have concatenated? could they not have concatenated?
V-ing perfect
could I not have been concatenating? could you not have been concatenating? could he not have been concatenating? could we not have been concatenating? could you not have been concatenating? could they not have been concatenating?