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