I could arrive you could arrive she could arrive we could arrive you could arrive they could arrive
V-ing form
I could be arriving you could be arriving she could be arriving we could be arriving you could be arriving they could be arriving
Perfect
I could have arrived you could have arrived she could have arrived we could have arrived you could have arrived they could have arrived
V-ing perfect
I could have been arriving you could have been arriving she could have been arriving we could have been arriving you could have been arriving they could have been arriving
Negation
Simple form
I couldn't arrive you couldn't arrive she couldn't arrive we couldn't arrive you couldn't arrive they couldn't arrive
V-ing form
I couldn't be arriving you couldn't be arriving she couldn't be arriving we couldn't be arriving you couldn't be arriving they couldn't be arriving
Perfect
I couldn't have arrived you couldn't have arrived she couldn't have arrived we couldn't have arrived you couldn't have arrived they couldn't have arrived
V-ing perfect
I couldn't have been arriving you couldn't have been arriving she couldn't have been arriving we couldn't have been arriving you couldn't have been arriving they couldn't have been arriving
Interrogative form
Simple form
could I arrive? could you arrive? could she arrive? could we arrive? could you arrive? could they arrive?
V-ing form
could I be arriving? could you be arriving? could she be arriving? could we be arriving? could you be arriving? could they be arriving?
Perfect
could I have arrived? could you have arrived? could she have arrived? could we have arrived? could you have arrived? could they have arrived?
V-ing perfect
could I have been arriving? could you have been arriving? could she have been arriving? could we have been arriving? could you have been arriving? could they have been arriving?
Interro-negative form
Simple form
couldn't I arrive? couldn't you arrive? couldn't she arrive? couldn't we arrive? couldn't you arrive? couldn't they arrive?
V-ing form
couldn't I be arriving? couldn't you be arriving? couldn't she be arriving? couldn't we be arriving? couldn't you be arriving? couldn't they be arriving?
Perfect
couldn't I have arrived? couldn't you have arrived? couldn't she have arrived? couldn't we have arrived? couldn't you have arrived? couldn't they have arrived?
V-ing perfect
couldn't I have been arriving? couldn't you have been arriving? couldn't she have been arriving? couldn't we have been arriving? couldn't you have been arriving? couldn't they have been arriving?