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