第二部分 第六讲 复合句.pptVIP

例如： When (he was)asked about it，he kept silent. Fill in the blanks with articles when (they are)necessary. If (it is) possible，Ill explain it again later. She stood at the gate as if (she was) waiting for someone. Unless (he was) invited，he would never go to the party. (二)时间状语从句 1．“一……就……”的表达如下表： 词类 常用词 例句 从属连词 as soon as He started as soon as he received the news. 副词 immediately，directly，instantly They phoned immediately they reached home. 词类 常用词 例句 名词/名词短语 the minute /moment/second/instant，every/each time They ran away the moment they saw the guard. Each time I was in trouble，he would stand by. 句型结构 no sooner...than...，hardly/scarcely...when... No sooner had I arrived home than it began to rain. 2．till，until的用法 (1)肯定句中，主句谓语动词必须是延续性动词，意为“某 一动作一直延续到某时间点才停止”。例如： He remained there till/until she arrived. (2)否定句中，主句谓语动词必须是非延续性动词，从句 为肯定式，意为“某动作直到某时间才开始”。例如： I was not aware that I forgot my ticket till/until I got to the station. (3)till不可置于句首，until可以。 (4)强调和倒装句中，not...until应视为一个整体，同时 被强调或置于句首。例如： It was not until you told me that I had any idea of it. Not until you told me did I have any idea of it. 3．before和since的用法 (1)before常用于表示“还未……就，不到……就，……才， 趁……，还没来得及”等含义。例如： We had sailed four days and four nights before we saw land. He rushed out of the house before I could say anything else. (2)句型It was/will be＋时间段＋before...意为“过了多久 才……”。It was not long before.../it will not be long before...意为“不久就……”。例如： It will be one year and a half before I come back. It was not long before he sensed the danger of the position. (3)since从句的谓语动词一般是短暂动词，主句谓语动 词则是延续性动词或反复发生的动作。since引导的从句时态为一般过去时，主句时态为现在完成时或现在完成进行时。例如： She has been working for the company since she left school. (4)句型It is/has been＋时间段＋since...意为“自从……到 现在多久了”。例如： It is a long time since I saw you last time. ＝I have not seen you for a long time. It has been two years since I was admitted to this key middle school. ＝I was admitted to this key middle school two years ago. It is three years since I smoked a cigar. ＝It is three ye