04 状语从句-备战2023年中考英语核心语法精讲精练（全国通用）

状语从句 一、时间状语从句 要点: 时间状语从句，由以下连词引导： When，while，as，after，before，as soon as， since， till /until， by the time 在时间状语从句中，要注意时态一致。一般情况下主句是将来时的时候，从句要用一般现在时(主将从现）。 　　1. when Mozart started writing music when he was four years old. 　　2. while 　　He visited a lot of places while he was traveling. 　　3. as He smiled as he stood up. as/when/while的辨析 　　as、when、while都表示主、从句动作同时发生（均为当......的时候的意思），三者差异如下： ① as 表示“一边, 一边＂的意思,强调两个动作同时进行，并表示对比 ② when 1. 还可以表示从句动词的动作在主句动词的动作＂之前 ＂或＂之后＂发生。 　　 2. when＝and then; at that moment (正在那个时候) ③ while 1. 用于时间较长时（while 后常跟进行时） 2. 强调两个动作同时进行，并表示对比时 　　有时这三个连词可以互换，有时不可以。 　When I had read the article, he called me. 　When I got to the cinema, the film had begun. 　She thought I was talking about her daughter, while, in fact, I was talking about my daughter. 　While the alien was buying a souvenir, the girl called the police. Mother was worried because little Alice was ill, especially as father was away. 　　4. after 　　He left the classroom after he had finished his homework the other day. 　　5. before 　　Mr. Brown had worked in a bank for a year before he came here. 　　6. as soon as 　　We began to work as soon as we got there. 　　I will write to you as soon as I get home. 我一到家就给你写信。 　　7. since 　　表示自过去的一个起点时间到目前(说话时间)为止的一段持续时间。主句一般用现在完成时，从句用一般过去时。 　　Mr. Green has taught in that school since he came to china three years ago. 　　(还可以用作介词，本句从句还可以用短语：since three years ago(自三年前以来)表示。) 8. till /until till /until都可以作连词，连接时间状语，也可以作介词，与其它词构成介词短语，在句中作状语。（till/until 前常用延续性动词；not until 前常用短暂性动词） 　　They walked till /until it was dark. 　　Xiao Ming didn’t leave home till / until his father came back. 9. by the time ①by the time +一般现在时， 主句用现在完成时 ②by the time +一般过去时，主句用过去完成时） 　　By the time he gets there, his father has already gone. 　　By the time I got to school, the class had already began. 知识扩展 　　1. it is +时间段 since+一般过去时=it has been +时间段 since +一般过去时 　　It is five years since we met last time. 　　2. it is + 时间段before 　　It was a long time before I went to sleep aga