I could approach you could approach he could approach we could approach you could approach they could approach
V-ing form
I could be approaching you could be approaching he could be approaching we could be approaching you could be approaching they could be approaching
Perfect
I could have approached you could have approached he could have approached we could have approached you could have approached they could have approached
V-ing perfect
I could have been approaching you could have been approaching he could have been approaching we could have been approaching you could have been approaching they could have been approaching
Negation
Simple form
I could not approach you could not approach he could not approach we could not approach you could not approach they could not approach
V-ing form
I could not be approaching you could not be approaching he could not be approaching we could not be approaching you could not be approaching they could not be approaching
Perfect
I could not have approached you could not have approached he could not have approached we could not have approached you could not have approached they could not have approached
V-ing perfect
I could not have been approaching you could not have been approaching he could not have been approaching we could not have been approaching you could not have been approaching they could not have been approaching
Interrogative form
Simple form
could I approach? could you approach? could he approach? could we approach? could you approach? could they approach?
V-ing form
could I be approaching? could you be approaching? could he be approaching? could we be approaching? could you be approaching? could they be approaching?
Perfect
could I have approached? could you have approached? could he have approached? could we have approached? could you have approached? could they have approached?
V-ing perfect
could I have been approaching? could you have been approaching? could he have been approaching? could we have been approaching? could you have been approaching? could they have been approaching?
Interro-negative form
Simple form
could I not approach? could you not approach? could he not approach? could we not approach? could you not approach? could they not approach?
V-ing form
could I not be approaching? could you not be approaching? could he not be approaching? could we not be approaching? could you not be approaching? could they not be approaching?
Perfect
could I not have approached? could you not have approached? could he not have approached? could we not have approached? could you not have approached? could they not have approached?
V-ing perfect
could I not have been approaching? could you not have been approaching? could he not have been approaching? could we not have been approaching? could you not have been approaching? could they not have been approaching?