4、包括现在在内的一段时间的状语连用。ShehaslearnedEnglishfor5years.HehaslivedinBeijingsince5yearsago.since:(自…以来)1)since+时间点He has stayed heresince 5 o’clock.2)since+时间段+agoHe has stayed heresince 5 hours ago.3)since+从句She has taught Englishsince he came here.for:(长达)for+时间