I can solve you can solve he can solve we can solve you can solve they can solve
V-ing form
I can be solving you can be solving he can be solving we can be solving you can be solving they can be solving
Perfect
I can have solved you can have solved he can have solved we can have solved you can have solved they can have solved
V-ing perfect
I can have been solving you can have been solving he can have been solving we can have been solving you can have been solving they can have been solving
Negation
Simple form
I can't solve you can't solve he can't solve we can't solve you can't solve they can't solve
V-ing form
I can't be solving you can't be solving he can't be solving we can't be solving you can't be solving they can't be solving
Perfect
I can't have solved you can't have solved he can't have solved we can't have solved you can't have solved they can't have solved
V-ing perfect
I can't have been solving you can't have been solving he can't have been solving we can't have been solving you can't have been solving they can't have been solving
Interrogative form
Simple form
can I solve? can you solve? can he solve? can we solve? can you solve? can they solve?
V-ing form
can I be solving? can you be solving? can he be solving? can we be solving? can you be solving? can they be solving?
Perfect
can I have solved? can you have solved? can he have solved? can we have solved? can you have solved? can they have solved?
V-ing perfect
can I have been solving? can you have been solving? can he have been solving? can we have been solving? can you have been solving? can they have been solving?
Interro-negative form
Simple form
can't I solve? can't you solve? can't he solve? can't we solve? can't you solve? can't they solve?
V-ing form
can't I be solving? can't you be solving? can't he be solving? can't we be solving? can't you be solving? can't they be solving?
Perfect
can't I have solved? can't you have solved? can't he have solved? can't we have solved? can't you have solved? can't they have solved?
V-ing perfect
can't I have been solving? can't you have been solving? can't he have been solving? can't we have been solving? can't you have been solving? can't they have been solving?