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Luyện ngữ pháp - English Grammar in Use - Intermediate (Unit 116: As)

Grammar Explanations and Rules

As = at the same time as

You can use as when two things happen at the same time:

We all waved goodbye to Liz as she drove away. (We waved and she drove away at the same time)
As I walked along the street, I looked in the shop windows.
Can you turn off the light as you go out, please?

Or you can say that something happened as you were doing something else (in the middle of doing something else):

For the past continuous (was getting / were going etc.), see Unit 6

You can also use just as (= exactly at that moment):

We also use as when two things happen together in a longer period of time:

Compare as and when:

We use as only if two things happen at the same time.

Use when (not as) if one thing happens after another.

As = because

As also means 'because':

As I was hungry, I decided to find somewhere to eat. (= because I was hungry)
As we have plenty of time before our flight, let's go and have a coffee.
We watched TV all evening as we didn't have anything better to do.
As I don't watch television any more, I gave my TV to a friend of mine.

You can also use since in this way:

Compare as (= because) and when:

I couldn't contact David as he was on holiday. (= because he was on holiday)	David's passport was stolen when he was on holiday. (= during the time he was away)
As they lived near us, we used to see them quite often. (= because they lived near us)	When they lived near us, we used to see them quite often. (= at the time they lived near us)