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