I could slide you could slide he could slide we could slide you could slide they could slide
V-ing form
I could be sliding you could be sliding he could be sliding we could be sliding you could be sliding they could be sliding
Perfect
I could have slid you could have slid he could have slid we could have slid you could have slid they could have slid
V-ing perfect
I could have been sliding you could have been sliding he could have been sliding we could have been sliding you could have been sliding they could have been sliding
Negation
Simple form
I could not slide you could not slide he could not slide we could not slide you could not slide they could not slide
V-ing form
I could not be sliding you could not be sliding he could not be sliding we could not be sliding you could not be sliding they could not be sliding
Perfect
I could not have slid you could not have slid he could not have slid we could not have slid you could not have slid they could not have slid
V-ing perfect
I could not have been sliding you could not have been sliding he could not have been sliding we could not have been sliding you could not have been sliding they could not have been sliding
Interrogative form
Simple form
could I slide? could you slide? could he slide? could we slide? could you slide? could they slide?
V-ing form
could I be sliding? could you be sliding? could he be sliding? could we be sliding? could you be sliding? could they be sliding?
Perfect
could I have slid? could you have slid? could he have slid? could we have slid? could you have slid? could they have slid?
V-ing perfect
could I have been sliding? could you have been sliding? could he have been sliding? could we have been sliding? could you have been sliding? could they have been sliding?
Interro-negative form
Simple form
could I not slide? could you not slide? could he not slide? could we not slide? could you not slide? could they not slide?
V-ing form
could I not be sliding? could you not be sliding? could he not be sliding? could we not be sliding? could you not be sliding? could they not be sliding?
Perfect
could I not have slid? could you not have slid? could he not have slid? could we not have slid? could you not have slid? could they not have slid?
V-ing perfect
could I not have been sliding? could you not have been sliding? could he not have been sliding? could we not have been sliding? could you not have been sliding? could they not have been sliding?