I can discover you can discover she can discover we can discover you can discover they can discover
V-ing form
I can be discovering you can be discovering she can be discovering we can be discovering you can be discovering they can be discovering
Perfect
I can have discovered you can have discovered she can have discovered we can have discovered you can have discovered they can have discovered
V-ing perfect
I can have been discovering you can have been discovering she can have been discovering we can have been discovering you can have been discovering they can have been discovering
Negation
Simple form
I can't discover you can't discover she can't discover we can't discover you can't discover they can't discover
V-ing form
I can't be discovering you can't be discovering she can't be discovering we can't be discovering you can't be discovering they can't be discovering
Perfect
I can't have discovered you can't have discovered she can't have discovered we can't have discovered you can't have discovered they can't have discovered
V-ing perfect
I can't have been discovering you can't have been discovering she can't have been discovering we can't have been discovering you can't have been discovering they can't have been discovering
Interrogative form
Simple form
can I discover? can you discover? can she discover? can we discover? can you discover? can they discover?
V-ing form
can I be discovering? can you be discovering? can she be discovering? can we be discovering? can you be discovering? can they be discovering?
Perfect
can I have discovered? can you have discovered? can she have discovered? can we have discovered? can you have discovered? can they have discovered?
V-ing perfect
can I have been discovering? can you have been discovering? can she have been discovering? can we have been discovering? can you have been discovering? can they have been discovering?
Interro-negative form
Simple form
can't I discover? can't you discover? can't she discover? can't we discover? can't you discover? can't they discover?
V-ing form
can't I be discovering? can't you be discovering? can't she be discovering? can't we be discovering? can't you be discovering? can't they be discovering?
Perfect
can't I have discovered? can't you have discovered? can't she have discovered? can't we have discovered? can't you have discovered? can't they have discovered?
V-ing perfect
can't I have been discovering? can't you have been discovering? can't she have been discovering? can't we have been discovering? can't you have been discovering? can't they have been discovering?