how do we know ( how has much time actually passed? )

이문장 옳게 고치면 어떻게 고치나요 ?? how do we know how much time has actually passed? 이거인가요??

그리고 한문제더

do you ever wonder (what did happen to) your old friends ?

이문장은 do you ever wonder (what happened to ) 이렇게 고치면 될까요 ??

알려주세요~