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