第 105 课 · 第 9 阶段: 连接观点
As = when / because
中级构成与用法
As I was leaving, the phone rang. As it was late, we took a taxi.
1.as 的两种意思
as 引导从句时（as + 主语 + 动词），通常有两种意思之一：when / while（当……时）或 because（因为）。上下文和动词时态可以帮你区分。
| 意思 | 通常搭配 | 例句 |
|---|---|---|
| 时间（= when / while） | 正在进行的动作，常用过去进行时 | As I was leaving, the phone rang. |
| 原因（= because / since） | 听者已经知道或能猜到的原因 | As it was late, we took a taxi. |
As 还有别的用法：as a teacher（作为——见“Like 与 as”一课）、as tall as（比较）。这一课只讲 as 连接两个从句的用法。
2.As = when、while
As 表示两件事同时发生。较长的背景动作常用过去进行时，在这期间发生的短暂动作用一般过去时（见“过去进行时”一课）。Just as = 恰好在那一刻。
As I was walking to work, I saw an accident.
我走路去上班的时候，看到了一起事故。
The phone rang just as I was getting into the shower.
我正要进去洗澡，电话就响了。
My hands were shaking as I opened the letter.
我拆信的时候手一直在抖。
两件事一起变化时也用 as：
As we got closer to the beach, we could hear the waves.
离海滩越来越近，我们听到了海浪声。
As the evening went on, the restaurant got busier.
随着夜色渐深，餐厅越来越热闹。
表示人生中的一段时期或较长的一段时间时，不要用 as：When I was a child, I lived in Hue（不说：As I was a child… —— 听者会理解成“因为我是个孩子”）。
3.As = because
As（和 since）表示原因，通常是听者已经知道的原因，或者不是重点的原因。as 从句常放在前面。当原因是主要信息时——特别是回答 Why…? 的时候——用 because。as 表示“因为”在英式英语中很常见；美国人更常用 since 或 because。
As it was a public holiday, the banks were closed.
因为是公共假日，银行都关门了。
As you're not busy, could you help me with this box?
既然你不忙，能帮我搬一下这个箱子吗？
We ordered pizza as nobody wanted to cook.
因为没人想做饭，我们就点了披萨。
Since you're here, let's start the meeting.
既然你来了，我们开会吧。（since = as）
中文习惯说“因为……所以……”。英语只用其中一个：As it was late, we took a taxi. / It was late, so we took a taxi. 不说 “As it was late, so we took a taxi”。
4.用 as、when、while 还是 because？
| 用于 | 例句 | |
|---|---|---|
| when | 某一时刻、一个短暂的动作或人生的一段时期 | When I was ten, we moved to Hue. |
| while | 在另一件事正在发生的过程中 | Someone called while you were out. |
| as | 两件事同时发生或一起变化；讲故事时常用 | As the bus pulled away, I realised I'd left my bag. |
| because | 原因是主要信息 | I'm late because my alarm didn't go off. |
| as / since | 已知的原因，常放在句首 | As it's raining, let's stay in. |
有时 as 两种理解都说得通。如果想表达得完全清楚，就用 while（时间）或 because（原因）。
As I was cooking, the lights went out.
我做饭的时候，突然停电了。（时间）
As I was cooking, I couldn't answer the phone.
我在做饭，没法接电话。（时间或原因——两种理解都可以）
As Huy was ill, he stayed at home.
因为阿辉病了，他待在家里。（状态 → 原因）
5.常见错误
As it was late, so we took a taxi.As it was late, we took a taxi.
as 和 so 不要一起用。
Like it was raining, we stayed home.As it was raining, we stayed home.
Like 不能表示“因为”。
As I was a child, I lived in Hue.When I was a child, I lived in Hue.
表示人生的一段时期用 when。
As I was cooking, I was cutting my finger.As I was cooking, I cut my finger.
短暂的动作用一般过去时。
Why did you leave early? — As I felt sick.Why did you leave early? — Because I felt sick.
回答 Why 用 because。
例句
- As I was walking home, it started to rain.
- As it was a holiday, the streets were very quiet.
- As I didn't have any cash, I paid by card.
- Minh arrived as we were having dinner.
