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