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