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 couldn't send you couldn't send he couldn't send we couldn't send you couldn't send they couldn't send
V-ing form
I couldn't be sending you couldn't be sending he couldn't be sending we couldn't be sending you couldn't be sending they couldn't be sending
Perfect
I couldn't have sent you couldn't have sent he couldn't have sent we couldn't have sent you couldn't have sent they couldn't have sent
V-ing perfect
I couldn't have been sending you couldn't have been sending he couldn't have been sending we couldn't have been sending you couldn't have been sending they couldn't 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
couldn't I send? couldn't you send? couldn't he send? couldn't we send? couldn't you send? couldn't they send?
V-ing form
couldn't I be sending? couldn't you be sending? couldn't he be sending? couldn't we be sending? couldn't you be sending? couldn't they be sending?
Perfect
couldn't I have sent? couldn't you have sent? couldn't he have sent? couldn't we have sent? couldn't you have sent? couldn't they have sent?
V-ing perfect
couldn't I have been sending? couldn't you have been sending? couldn't he have been sending? couldn't we have been sending? couldn't you have been sending? couldn't they have been sending?