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