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Since 的用法和判别 | 新编英语阅读手册

Since 的用法和判别

Since 的用法和判别

一、since 的四种用法

I. 引导原因从句:since 表示原因的意味稍弱,常译为“既然”,有时也可译“因为”。

  1. Since displacement has direction, velocity also has direction. 既然物体的位移有方向,因此速度也有方向。
  2. Since heat and work are convertible, the most important thing to know about any device is its efficiency. 既然热和功可以相互转换,那么对任何机械要了解的最重要的问题就是它的效率。(to know about 为 thing 的定语。)
  3. Since (或 As) you do not know, therefore I shall have to tell you. 既然你不知道,所以我就不得不告诉你。(注意由 sinceas 引出的原因状语从句,其后面的主句还可用 therefore 与之相呼应。但这都用于正式文体中。注意不能用 then 代替 therefore。)

注:常可用 inasmuch as (或 in as much as) 代替 since,以引出原因状语从句,但前者多用于书面语中。例如:

Inasmuch as (或 In as much as) it is not your fault, you needn't care. 既然这不是你的错,你就不必介意了。(也可用 since 代之。)

II. 引导时间从句,一般可译为“自从……以来”。

  1. Nearly two thousand years has (或 have) passed since the Chinese first invented the compass. 自从中国人最先发明指南针以来,已过了近两千年了。
  2. It is (或 has been) five years since I visited your father. 我已有五年没有拜访你的父亲了。(由“自从我拜访过你的父亲以来已有五年时间了”引申过来。)
  3. It is five years since he taught English. 他不教英语已有五年。(仍按上例去理解。)
  4. It is (或 has been) three years since she was a nurse. 她不当护士已有三年了。(由“自从她当过护士即后来不当护士以来已有三年”引申过来。)
  5. It is a week since they left for Japan. 他们去日本已有一周了。(“他们离开这里去日本”的结果是“他们走了一不在这里”。故译为“去日本一周”是合适的。)

III. 介词 since 后接一个名词(有时接副词或短语),多半作时间状语可译为“自从…以来”。偶然作后置定语。

  1. We have made great achievements since 1978 (或 since twenty two years ago). 自从1978年(或22午前)以来我们取得了伟大的成就。(这是站在 2000 年角度说上面这句话。)
  2. I have not visited Europe any more since then. 从那时起,我再也没有访问过欧洲。
  3. Since when has be been living here? 从何时起他一直住在这里?
  4. How many periods does the history since 1949 fall into? 1949 年以后的历史可分为几个阶段呢?(注意 since 1949 不作状语,而作 the history 的定语。)

Ⅳ. 作副词用,可译为“从此以后”意思。

  1. I met him in 1969 and have not seen him since. 我在 1969 年见过他,此后一直没有见到他。
  2. She left home a week ago and I haven't heard from her since. 她一周以前离家,从那时起我一直未听到她的音讯。

二、since 用法的判别

I. 如果主句用完成时态,则 since 引导的从句通常是时间从句,除此以外,大多是原因从句。例如:

  1. Computer shave found world-wide application since they were invented. 电从发明以来,就在世界范围内得到了广泛的应用。(时间从句)
  2. They have been discussing the plan since we entered the meeting room. 从我们进入会议室以来,他们一直在讨论计划。(时间从句)
  3. Since energy is defined the capacity to do work, we measure energy in units of work. 既然对能下的定义是作功的本领,因此我们就用功的单位来计量能的大小。(原因从句)

II. 当主句的主、谓语是 it is (或 was) 时,只有当 since 引导的从句内的动词是过去时或过去完成时的形式时,since 才作“自从……以来”解:

It is (was) two years since we improved (或 had improved) these tools. 自从我们改进这些工具以来,已经过了两年。(用括弧内词则译为:自从我们改进这些工具以来,当时已经有两年了。)必须指出,上句中的 is 也可用 has been 代之。近来也有趋势想用现在完成时代替 since 引出的时间状语从句内常用的一般过去时。

III. 至于 since 和名词构成介词短语,一般作时间状语用。since 单独使用时,一般作副词用。


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