Example: "I've been to Greece (before)." When you are being more precise about the exact time period you visited, you cannot use "have been". You need to use "went". Example: "I went to …
∗ 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.
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