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