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 couldn't approach you couldn't approach he couldn't approach we couldn't approach you couldn't approach they couldn't approach
V-ing form
I couldn't be approaching you couldn't be approaching he couldn't be approaching we couldn't be approaching you couldn't be approaching they couldn't be approaching
Perfect
I couldn't have approached you couldn't have approached he couldn't have approached we couldn't have approached you couldn't have approached they couldn't have approached
V-ing perfect
I couldn't have been approaching you couldn't have been approaching he couldn't have been approaching we couldn't have been approaching you couldn't have been approaching they couldn't 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
couldn't I approach? couldn't you approach? couldn't he approach? couldn't we approach? couldn't you approach? couldn't they approach?
V-ing form
couldn't I be approaching? couldn't you be approaching? couldn't he be approaching? couldn't we be approaching? couldn't you be approaching? couldn't they be approaching?
Perfect
couldn't I have approached? couldn't you have approached? couldn't he have approached? couldn't we have approached? couldn't you have approached? couldn't they have approached?
V-ing perfect
couldn't I have been approaching? couldn't you have been approaching? couldn't he have been approaching? couldn't we have been approaching? couldn't you have been approaching? couldn't they have been approaching?