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