I can study you can study she can study we can study you can study they can study
V-ing form
I can be studying you can be studying she can be studying we can be studying you can be studying they can be studying
Perfect
I can have studied you can have studied she can have studied we can have studied you can have studied they can have studied
V-ing perfect
I can have been studying you can have been studying she can have been studying we can have been studying you can have been studying they can have been studying
Negation
Simple form
I cannot study you cannot study she cannot study we cannot study you cannot study they cannot study
V-ing form
I cannot be studying you cannot be studying she cannot be studying we cannot be studying you cannot be studying they cannot be studying
Perfect
I cannot have studied you cannot have studied she cannot have studied we cannot have studied you cannot have studied they cannot have studied
V-ing perfect
I cannot have been studying you cannot have been studying she cannot have been studying we cannot have been studying you cannot have been studying they cannot have been studying
Interrogative form
Simple form
can I study? can you study? can she study? can we study? can you study? can they study?
V-ing form
can I be studying? can you be studying? can she be studying? can we be studying? can you be studying? can they be studying?
Perfect
can I have studied? can you have studied? can she have studied? can we have studied? can you have studied? can they have studied?
V-ing perfect
can I have been studying? can you have been studying? can she have been studying? can we have been studying? can you have been studying? can they have been studying?
Interro-negative form
Simple form
can I not study? can you not study? can she not study? can we not study? can you not study? can they not study?
V-ing form
can I not be studying? can you not be studying? can she not be studying? can we not be studying? can you not be studying? can they not be studying?
Perfect
can I not have studied? can you not have studied? can she not have studied? can we not have studied? can you not have studied? can they not have studied?
V-ing perfect
can I not have been studying? can you not have been studying? can she not have been studying? can we not have been studying? can you not have been studying? can they not have been studying?