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        英語語法中since的用法

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            since的四種用法
            1) since +過去一個(gè)時(shí)間點(diǎn) (如具體的年、月、日期、鐘點(diǎn)、1980, last month, half past six)。
            I have been here since 1989.
            2) since +一段時(shí)間+ ago
            I have been here since five months ago.
            3) since +從句
            Great changes have taken place since you left.
            Considerable time has elapsed since we have been here.
            4) It is +一段時(shí)間+ since從句
            It is two years since I became a postgraduate student.