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