when to use "should have"?


I have a question, I have read this sentence:

the Western powers now yielded when they should have resisted

but I do not understand why they use the present perfect at the end of the sentence 'have resisted' after the auxiliary verb should.


Posted 2015-05-17T22:35:38.923

Reputation: 617

1That is not a present perfect. The expression "they should have resisted" uses a non-finite perfect *"have resisted"*, and that "have" is not tensed. The tensed verb is the verb "should". – F.E. – 2015-05-17T23:41:56.043


Mohammad, please allow at least a day or two before accepting an answer. For info about why this is helpful, see “Not so fast! (When should I accept my answer?)”. This question really deserves an in-depth response.

– Ben Kovitz – 2015-05-18T02:06:03.723



Here is the best answer to your question:

We can use 'should have' to talk about past events that did not happen.

  • I should have let her know what was happening but I forgot.
  • He should have sent everybody a reminder by email.
  • They should have remembered that their guests don't eat pork.


Posted 2015-05-17T22:35:38.923

Reputation: 617

Good reference. :) – LawrenceC – 2015-05-17T22:57:56.307