如果是持续性动词,句子的主要部分可用肯定式也可用否定式:
I watched TV until mom came back.(看电视的动作一直持续到妈妈回来)
I didnt watch TV until mom came back.(妈妈回来才开始看电视)
如果是非持续性动词则必须用否定式即 not until :
I didnt begin to watch TV until mom came back.(这句话主句就不可用肯定形式)
如果是持续性动词,句子的主要部分可用肯定式也可用否定式:
I watched TV until mom came back.(看电视的动作一直持续到妈妈回来)
I didnt watch TV until mom came back.(妈妈回来才开始看电视)
如果是非持续性动词则必须用否定式即 not until :
I didnt begin to watch TV until mom came back.(这句话主句就不可用肯定形式)