since 的四种用法 1) since +过去一个时间点(如具体的年、月、日期、钟点、1980, last month, half past six)。 I have been here since 1989. 2) since +一段时间+ ago I have been here since five months ago. 3) since +从句 Great changes have taken place since you left. Considerable time has elapsed since we have been here. 4) It is +一段时间+ since 从句 It is two years since I became a postgraduate student.延续动词与瞬间动词 1) 用于完成时的区别 延续动词表示经验、 经历\ue039 瞬间动词表示行为的结 果\ue036 不能与表示段的时间状语连用。 He has completed the work.他已完成了那项工作。 (表结果) I've known him since then. 我从那时起就认识他了。(表经历) 2)用于 till / until 从句的差异 作为延续动词一般用于肯定句\ue036 表示"做„„直到„„" 作为瞬间动词一般用于否定句\ue036表示"到„„\ue036才„„" He didn't come back until ten o'clock. 他到 10 点才回来。 He slept tll ten o'clock. 他一直睡到 10 点。典型例题 1. You don't need to describe her. I ___ her several times. A. had met B. have met C. met D. meet 答案 B. 首先本题后句强调对现在的影响\ue036我知道她的模样\ue036你不用描述。再次\ue036several times 告知为反复发生的动作\ue036 因此用现在完成时。 2.---I'm sorry to keep you waiting. ---Oh, not at all. I ___ here only a few minutes. A. have been B. had been C. was D. will be 答案 A. 等待的动作由过去开始\ue036持续到现在\ue036应用现在完成时。 回答人的补充 2010-05-31 17:51 反义疑问句(The Disjunctive Question) 即附加疑问句。它表示提问人的看法,没有把握,需要对方证实。 反义疑问句由两部分组成\ue038前一部分是一个陈述句\ue036后一部分是一个简短的疑问句\ue036两部分的人称时态应保持一致。 1\ue037 陈述部分肯定式+疑问部分否定式 可记为 前肯后否 2\ue037陈述部分否定式+疑问部分肯定式 可记为 前否后肯 They work hard, don’t they? She was ill yesterday, wasn’t she? You didn’t go, did you? He can’t ride a bike, can he? He is a student,isn't he?[编辑本段]特殊的句型 请注意以下句型的反义疑问句的用法\ue038 1\ue037 当陈述部分的主语是 I , everyone, everything, nobody 时\ue036后面的疑问句应表示为\ue038 I am a student, aren’t I ? Everyone is in the classroom, aren’t they? (基本不用单数\ue035 Nobody will go, will they? 2. 否定 \ue0341\ue035当陈述部分有 never\ue036seldom, hardly\ue036few\ue036little\ue036barely, scarcely, nothing 等否定词时\ue036后面的疑问句则为肯定形式\ue038 There are few apples in the basket, are there? He can hardly swim, can he? They seldom come late, do they? \ue0342\ue035当陈述部分含有否定意思的词是unhappy,dislike,unfriendly 等含有否定词缀的派生词时\ue036疑问部分要用否定形式。