I know her. (Maybe for only two days, but I know her) I`ve known her for years. (I've known her for a long time.) He impressed me with his history. (At one point in the past he impressed me.) He has impressed me with his history. (He impressed me for a span of time in the past.) He impresses me with his history. (He continues to impress me today.) She owns two car. (cars) She has got two car. (The same thing really. Has implies ownership, or at least possession. She has two cars is a better way to say it.) He didn`t remember my name. (At some point in the past he didn't remember.) He has not remembered my name. (He didn't remember in the past and he still doesn't remember.)