I could shake you could shake she could shake we could shake you could shake they could shake
V-ing form
I could be shaking you could be shaking she could be shaking we could be shaking you could be shaking they could be shaking
Perfect
I could have shaken you could have shaken she 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 she 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 she 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 she 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 she 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 she 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 she shake? could we shake? could you shake? could they shake?
V-ing form
could I be shaking? could you be shaking? could she be shaking? could we be shaking? could you be shaking? could they be shaking?
Perfect
could I have shaken? could you have shaken? could she 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 she 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 she 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 she 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 she 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 she have been shaking? couldn't we have been shaking? couldn't you have been shaking? couldn't they have been shaking?