I can fall you can fall she can fall we can fall you can fall they can fall
V-ing form
I can be falling you can be falling she can be falling we can be falling you can be falling they can be falling
Perfect
I can have fallen you can have fallen she can have fallen we can have fallen you can have fallen they can have fallen
V-ing perfect
I can have been falling you can have been falling she can have been falling we can have been falling you can have been falling they can have been falling
Negation
Simple form
I can't fall you can't fall she can't fall we can't fall you can't fall they can't fall
V-ing form
I can't be falling you can't be falling she can't be falling we can't be falling you can't be falling they can't be falling
Perfect
I can't have fallen you can't have fallen she can't have fallen we can't have fallen you can't have fallen they can't have fallen
V-ing perfect
I can't have been falling you can't have been falling she can't have been falling we can't have been falling you can't have been falling they can't have been falling
Interrogative form
Simple form
can I fall? can you fall? can she fall? can we fall? can you fall? can they fall?
V-ing form
can I be falling? can you be falling? can she be falling? can we be falling? can you be falling? can they be falling?
Perfect
can I have fallen? can you have fallen? can she have fallen? can we have fallen? can you have fallen? can they have fallen?
V-ing perfect
can I have been falling? can you have been falling? can she have been falling? can we have been falling? can you have been falling? can they have been falling?
Interro-negative form
Simple form
can't I fall? can't you fall? can't she fall? can't we fall? can't you fall? can't they fall?
V-ing form
can't I be falling? can't you be falling? can't she be falling? can't we be falling? can't you be falling? can't they be falling?
Perfect
can't I have fallen? can't you have fallen? can't she have fallen? can't we have fallen? can't you have fallen? can't they have fallen?
V-ing perfect
can't I have been falling? can't you have been falling? can't she have been falling? can't we have been falling? can't you have been falling? can't they have been falling?