should fail
Regular verb: fail - failed- failed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I should fail
you should fail
he should fail
we should fail
you should fail
they should fail 	I should be failing
you should be failing
he should be failing
we should be failing
you should be failing
they should be failing	I should have failed
you should have failed
he should have failed
we should have failed
you should have failed
they should have failed	I should have been failing
you should have been failing
he should have been failing
we should have been failing
you should have been failing
they should have been failing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I should not fail
you should not fail
he should not fail
we should not fail
you should not fail
they should not fail 	I should not be failing
you should not be failing
he should not be failing
we should not be failing
you should not be failing
they should not be failing	I should not have failed
you should not have failed
he should not have failed
we should not have failed
you should not have failed
they should not have failed	I should not have been failing
you should not have been failing
he should not have been failing
we should not have been failing
you should not have been failing
they should not have been failing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I fail?
should you fail?
should he fail?
should we fail?
should you fail?
should they fail? 	should I be failing?
should you be failing?
should he be failing?
should we be failing?
should you be failing?
should they be failing? 	should I have failed?
should you have failed?
should he have failed?
should we have failed?
should you have failed?
should they have failed? 	should I have been failing?
should you have been failing?
should he have been failing?
should we have been failing?
should you have been failing?
should they have been failing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I not fail?
should you not fail?
should he not fail?
should we not fail?
should you not fail?
should they not fail? 	should I not be failing?
should you not be failing?
should he not be failing?
should we not be failing?
should you not be failing?
should they not be failing? 	should I not have failed?
should you not have failed?
should he not have failed?
should we not have failed?
should you not have failed?
should they not have failed? 	should I not have been failing?
should you not have been failing?
should he not have been failing?
should we not have been failing?
should you not have been failing?
should they not have been failing?