Lesson 105 · Stage 9: Linking ideas
As = when / because
IntermediateForm & use
As I was leaving, the phone rang. As it was late, we took a taxi.
1.The two meanings of as
When as begins a clause (as + subject + verb), it usually has one of two meanings: when / while or because. The context and the verb tense help you tell them apart.
| Meaning | Usually with | Example |
|---|---|---|
| time (= when / while) | an action in progress, often the past continuous | As I was leaving, the phone rang. |
| reason (= because / since) | a reason the listener knows or can guess | As it was late, we took a taxi. |
As has other uses too: as a teacher (in the role of — see the lesson “Like vs as”), as tall as (comparisons). This lesson is only about as joining two clauses.
2.As = when, while
As shows that two things happen at the same time. The longer background action is often in the past continuous, and the short action that happens during it is in the past simple (see the lesson “Past continuous”). Just as = at exactly the moment.
As I was walking to work, I saw an accident.
The phone rang just as I was getting into the shower.
My hands were shaking as I opened the letter.
As is also used when two things change together:
As we got closer to the beach, we could hear the waves.
As the evening went on, the restaurant got busier.
Don't use as for a period of your life or a long stretch of time: When I was a child, I lived in Hue (not: As I was a child… — listeners would hear it as “because I was a child”).
3.As = because
As (and since) give a reason, usually one the listener already knows or that isn't the main point. The as clause often comes first. When the reason is the main news — especially in answer to Why…? — use because. As meaning “because” is common in British English; Americans tend to use since or because.
As it was a public holiday, the banks were closed.
As you're not busy, could you help me with this box?
We ordered pizza as nobody wanted to cook.
Since you're here, let's start the meeting.
since = as
Some languages pair “because … so …”. English uses only one of them: As it was late, we took a taxi. / It was late, so we took a taxi. Not “As it was late, so we took a taxi”.
4.As, when, while or because?
| Use it for | Example | |
|---|---|---|
| when | a moment, a short action, or a period of life | When I was ten, we moved to Hue. |
| while | during the time something else is happening | Someone called while you were out. |
| as | two things at the same time or changing together; common in stories | As the bus pulled away, I realised I'd left my bag. |
| because | the reason is the main news | I'm late because my alarm didn't go off. |
| as / since | a known reason, often at the start | As it's raining, let's stay in. |
Sometimes as can be read both ways. If you want to be completely clear, use while (time) or because (reason).
As I was cooking, the lights went out.
time
As I was cooking, I couldn't answer the phone.
time or reason — both readings possible
As Huy was ill, he stayed at home.
a state → reason
5.Common mistakes
As it was late, so we took a taxi.As it was late, we took a taxi.
Don't use as and so together.
Like it was raining, we stayed home.As it was raining, we stayed home.
Like can't mean “because”.
As I was a child, I lived in Hue.When I was a child, I lived in Hue.
Use when for a period of life.
As I was cooking, I was cutting my finger.As I was cooking, I cut my finger.
A short action takes the past simple.
Why did you leave early? — As I felt sick.Why did you leave early? — Because I felt sick.
Answer Why with because.
Examples
- 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.
