The present perfectThe aspect expressing completion. E.g.: He’s finished university. tenseA grammatical category that is marked by verb inflection. To express when an event or action happens in time or when a state exists, we use tenses. is used for recent actionA general term expressing that somebody or something does somethings that have a result in or an effect on the present.

Someone has opened the window.

Here we want to emphasisSpecial importance or attention given to something. E.g.: All I wanna do is have some fun.e that the window is open. The sentence suggests that it is probably cold inside. Compare with this one:

Someone opened the window.

This sentence simply states a fact. Whether the window is open or not is not important. The focusThe main or central point of attention or interest; what is emphasized. E.g.: All I wanna do is have some fun. ("all") is on the action, not the result or the effect of that action.

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Spring has come.

Present perfect for past actions
Present perfect Present perfect with an incomplete period