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