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