I can require you can require he can require we can require you can require they can require
V-ing form
I can be requiring you can be requiring he can be requiring we can be requiring you can be requiring they can be requiring
Perfect
I can have required you can have required he can have required we can have required you can have required they can have required
V-ing perfect
I can have been requiring you can have been requiring he can have been requiring we can have been requiring you can have been requiring they can have been requiring
Negation
Simple form
I cannot require you cannot require he cannot require we cannot require you cannot require they cannot require
V-ing form
I cannot be requiring you cannot be requiring he cannot be requiring we cannot be requiring you cannot be requiring they cannot be requiring
Perfect
I cannot have required you cannot have required he cannot have required we cannot have required you cannot have required they cannot have required
V-ing perfect
I cannot have been requiring you cannot have been requiring he cannot have been requiring we cannot have been requiring you cannot have been requiring they cannot have been requiring
Interrogative form
Simple form
can I require? can you require? can he require? can we require? can you require? can they require?
V-ing form
can I be requiring? can you be requiring? can he be requiring? can we be requiring? can you be requiring? can they be requiring?
Perfect
can I have required? can you have required? can he have required? can we have required? can you have required? can they have required?
V-ing perfect
can I have been requiring? can you have been requiring? can he have been requiring? can we have been requiring? can you have been requiring? can they have been requiring?
Interro-negative form
Simple form
can I not require? can you not require? can he not require? can we not require? can you not require? can they not require?
V-ing form
can I not be requiring? can you not be requiring? can he not be requiring? can we not be requiring? can you not be requiring? can they not be requiring?
Perfect
can I not have required? can you not have required? can he not have required? can we not have required? can you not have required? can they not have required?
V-ing perfect
can I not have been requiring? can you not have been requiring? can he not have been requiring? can we not have been requiring? can you not have been requiring? can they not have been requiring?