∗ I am widely travelled: I have been living in Europe for two years, in Brazil for nearly five, and in Singapore for three. † For a somewhat more detailed description of these distinct uses of …
For a valid Present Tense utterance, there's The room should be cleaned - where the speaker might mean It is desirable / right and proper that someone should clean this room (in the future; …
Has since finalized is much better. So in my opinion your sentence will be like that: The company opened its doors in May 2015 and has since finalized all the contracts. (Present …
That's why has been detected would be the correct choice here: There are two particles: quarks and gluons. Neither (one) has been detected in the lab in isolated form yet.
1. 'Was created' implies that it was created some time in the past but exactly when is unimportant. 'has been created' implies the event occurred very recently. – James. May …
更多内容请点击：Difference between 'should have and should have been'