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