I should investigate you should investigate she should investigate we should investigate you should investigate they should investigate
V-ing form
I should be investigating you should be investigating she should be investigating we should be investigating you should be investigating they should be investigating
Perfect
I should have investigated you should have investigated she should have investigated we should have investigated you should have investigated they should have investigated
V-ing perfect
I should have been investigating you should have been investigating she should have been investigating we should have been investigating you should have been investigating they should have been investigating
Negation
Simple form
I should not investigate you should not investigate she should not investigate we should not investigate you should not investigate they should not investigate
V-ing form
I should not be investigating you should not be investigating she should not be investigating we should not be investigating you should not be investigating they should not be investigating
Perfect
I should not have investigated you should not have investigated she should not have investigated we should not have investigated you should not have investigated they should not have investigated
V-ing perfect
I should not have been investigating you should not have been investigating she should not have been investigating we should not have been investigating you should not have been investigating they should not have been investigating
Interrogative form
Simple form
should I investigate? should you investigate? should she investigate? should we investigate? should you investigate? should they investigate?
V-ing form
should I be investigating? should you be investigating? should she be investigating? should we be investigating? should you be investigating? should they be investigating?
Perfect
should I have investigated? should you have investigated? should she have investigated? should we have investigated? should you have investigated? should they have investigated?
V-ing perfect
should I have been investigating? should you have been investigating? should she have been investigating? should we have been investigating? should you have been investigating? should they have been investigating?
Interro-negative form
Simple form
should I not investigate? should you not investigate? should she not investigate? should we not investigate? should you not investigate? should they not investigate?
V-ing form
should I not be investigating? should you not be investigating? should she not be investigating? should we not be investigating? should you not be investigating? should they not be investigating?
Perfect
should I not have investigated? should you not have investigated? should she not have investigated? should we not have investigated? should you not have investigated? should they not have investigated?
V-ing perfect
should I not have been investigating? should you not have been investigating? should she not have been investigating? should we not have been investigating? should you not have been investigating? should they not have been investigating?