Present Perfect Tense:
Present Perfect is used to:
-Indicate completed activities. – He has just left the office.
-express past actions whose time is not given and is indefinite. – I have never known him to be angry.
-describe past events when we think of their effect rather the action. I have cut my finger (and now it bleeding).
-denote an action beginning at some time in the past and continuing up to the present (We have lived here for eight months).