I could advance you could advance he could advance we could advance you could advance they could advance
V-ing form
I could be advancing you could be advancing he could be advancing we could be advancing you could be advancing they could be advancing
Perfect
I could have advanced you could have advanced he could have advanced we could have advanced you could have advanced they could have advanced
V-ing perfect
I could have been advancing you could have been advancing he could have been advancing we could have been advancing you could have been advancing they could have been advancing
Negation
Simple form
I couldn't advance you couldn't advance he couldn't advance we couldn't advance you couldn't advance they couldn't advance
V-ing form
I couldn't be advancing you couldn't be advancing he couldn't be advancing we couldn't be advancing you couldn't be advancing they couldn't be advancing
Perfect
I couldn't have advanced you couldn't have advanced he couldn't have advanced we couldn't have advanced you couldn't have advanced they couldn't have advanced
V-ing perfect
I couldn't have been advancing you couldn't have been advancing he couldn't have been advancing we couldn't have been advancing you couldn't have been advancing they couldn't have been advancing
Interrogative form
Simple form
could I advance? could you advance? could he advance? could we advance? could you advance? could they advance?
V-ing form
could I be advancing? could you be advancing? could he be advancing? could we be advancing? could you be advancing? could they be advancing?
Perfect
could I have advanced? could you have advanced? could he have advanced? could we have advanced? could you have advanced? could they have advanced?
V-ing perfect
could I have been advancing? could you have been advancing? could he have been advancing? could we have been advancing? could you have been advancing? could they have been advancing?
Interro-negative form
Simple form
couldn't I advance? couldn't you advance? couldn't he advance? couldn't we advance? couldn't you advance? couldn't they advance?
V-ing form
couldn't I be advancing? couldn't you be advancing? couldn't he be advancing? couldn't we be advancing? couldn't you be advancing? couldn't they be advancing?
Perfect
couldn't I have advanced? couldn't you have advanced? couldn't he have advanced? couldn't we have advanced? couldn't you have advanced? couldn't they have advanced?
V-ing perfect
couldn't I have been advancing? couldn't you have been advancing? couldn't he have been advancing? couldn't we have been advancing? couldn't you have been advancing? couldn't they have been advancing?