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