英语单词辨析 - As, because or since

As, because or since

ref：原文

概述：

As、because和since都是连词。As、because和since都用来引导从句。它们将某件事的结果和其原因联系起来。

Because：

Because" 比 “as” 和 “since” 更常用，无论是在写作还是在口语中。当我们使用 “because” 时，我们专注于原因：

She spoke quietly because she didn’t want Catherine to hear.

We’ll come over on Sunday because David’s got to work on Saturday.

我们经常将因为从句放在句子的开头，尤其是当我们想要特别强调原因时。我们在因为从句后面使用逗号：

Because breathing is something we do automatically, we rarely think about it.

在口语或非正式写作中，我们可以单独使用因为从句而不需要主句：

A: Would you like to go to school there?
B: Yes.
A: Why?
B: Because my best friend goes there. (I would like to go to school there because my best friend goes there.)

警告：

我们在正式写作中不单独使用because从句：

In 1998, the government introduced a new import tax because people were importing cars from abroad.
Not: … a new import tax. Because people were importing cars from abroad.

Cos

在非正式口语和写作中，我们经常将because缩写为cos /kəz/ 或 /kɒz/：

I’m laughing cos I’m so happy.

As and since

我们经常使用as和since当我们想更专注于结果而非原因时。As和since比because更正式。在主句之后的since前通常会用逗号：

I hope they’ve decided to come as I wanted to hear about their India trip.

They’re rather expensive, since they’re quite hard to find.

我们经常在句子开头使用as和since从句。在as或since从句之后使用逗号：

Since everything can be done from home with computers and telephones, there’s no need to dress up for work any more.

As everyone already knows each other, there’s no need for introductions. We’ll get straight into the business of the meeting.

我们在提出原因的问题中使用because，而不是as或since：

Are you feeling unwell because you ate too much?
Not: Are you feeling unwell since you ate too much? or … as you ate too much?