I could send you could send he could send we could send you could send they could send
V-ing form
I could be sending you could be sending he could be sending we could be sending you could be sending they could be sending
Perfect
I could have sent you could have sent he could have sent we could have sent you could have sent they could have sent
V-ing perfect
I could have been sending you could have been sending he could have been sending we could have been sending you could have been sending they could have been sending
Negation
Simple form
I could not send you could not send he could not send we could not send you could not send they could not send
V-ing form
I could not be sending you could not be sending he could not be sending we could not be sending you could not be sending they could not be sending
Perfect
I could not have sent you could not have sent he could not have sent we could not have sent you could not have sent they could not have sent
V-ing perfect
I could not have been sending you could not have been sending he could not have been sending we could not have been sending you could not have been sending they could not have been sending
Interrogative form
Simple form
could I send? could you send? could he send? could we send? could you send? could they send?
V-ing form
could I be sending? could you be sending? could he be sending? could we be sending? could you be sending? could they be sending?
Perfect
could I have sent? could you have sent? could he have sent? could we have sent? could you have sent? could they have sent?
V-ing perfect
could I have been sending? could you have been sending? could he have been sending? could we have been sending? could you have been sending? could they have been sending?
Interro-negative form
Simple form
could I not send? could you not send? could he not send? could we not send? could you not send? could they not send?
V-ing form
could I not be sending? could you not be sending? could he not be sending? could we not be sending? could you not be sending? could they not be sending?
Perfect
could I not have sent? could you not have sent? could he not have sent? could we not have sent? could you not have sent? could they not have sent?
V-ing perfect
could I not have been sending? could you not have been sending? could he not have been sending? could we not have been sending? could you not have been sending? could they not have been sending?