I can discover you can discover he can discover we can discover you can discover they can discover
V-ing form
I can be discovering you can be discovering he can be discovering we can be discovering you can be discovering they can be discovering
Perfect
I can have discovered you can have discovered he 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 he can have been discovering we can have been discovering you can have been discovering they can have been discovering
Negation
Simple form
I cannot discover you cannot discover he cannot discover we cannot discover you cannot discover they cannot discover
V-ing form
I cannot be discovering you cannot be discovering he cannot be discovering we cannot be discovering you cannot be discovering they cannot be discovering
Perfect
I cannot have discovered you cannot have discovered he cannot have discovered we cannot have discovered you cannot have discovered they cannot have discovered
V-ing perfect
I cannot have been discovering you cannot have been discovering he cannot have been discovering we cannot have been discovering you cannot have been discovering they cannot have been discovering
Interrogative form
Simple form
can I discover? can you discover? can he discover? can we discover? can you discover? can they discover?
V-ing form
can I be discovering? can you be discovering? can he be discovering? can we be discovering? can you be discovering? can they be discovering?
Perfect
can I have discovered? can you have discovered? can he 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 he have been discovering? can we have been discovering? can you have been discovering? can they have been discovering?
Interro-negative form
Simple form
can I not discover? can you not discover? can he not discover? can we not discover? can you not discover? can they not discover?
V-ing form
can I not be discovering? can you not be discovering? can he not be discovering? can we not be discovering? can you not be discovering? can they not be discovering?
Perfect
can I not have discovered? can you not have discovered? can he not have discovered? can we not have discovered? can you not have discovered? can they not have discovered?
V-ing perfect
can I not have been discovering? can you not have been discovering? can he not have been discovering? can we not have been discovering? can you not have been discovering? can they not have been discovering?