During or while? By or until? As or like?

A During or while?

Compare these examples.

I often read during a meal. I often read while I'm eating.

It happened during the night. It happened while they were asleep.

You'll have to be quiet during the performance. Were there any phone calls while I was out?

During is a preposition (like in). It comes before a phrase like a meal or the night.

While is a linking word (like when). It comes before a clause, e.g. I'm eating.

B By or until?

Compare these examples.

I'm very busy this week. I have to finish this report by Thursday.

I'll be busy for most of this week. I won't have any time until Friday.

Trevor will be home by half past six.

He'll be at work until half past five.

The post should be here by now.

They hope to build the new bridge by next July.

We won't have another holiday until next summer.

Till is more informal than until. I slept till ten o'clock.

We can use by the time or until before a clause, e.g. we arrived.

There was no food left by the time we arrived. NOT by we arrived

I'll wait until you're ready.

C As, like and as if

Compare these examples.

She works as a fashion model. She dresses like a fashion model.

(She is a model.) (Her clothes are similar to a model's.)

As a beginner you simply have to learn the basics. Mark is a good golfer, but today he played like a beginner.

I'm using this tin as an ashtray. You look like your brother.

We use as to talk about a job or function. We use like to talk about things being similar.

We can also use as or like before a clause.

We drive on the left here, as/like you do in Britain.

Mike and Sarah are going to Paris for the weekend, as/like they did last year.

Like is more informal than as before a clause.

We also use as with verbs of speaking and knowing, e.g. say, know, expect.

As I said before, I'm sorry. (I'm sorry, and I said so before.)

I haven't much money, as you know. (I haven't much money, and you know it.)

Rachel arrived late, as we expected. (We expected her to arrive late, and she did.)

We use as if before a clause to say how something seems.

Tom looks really awful. He looks as if he's been up all night.

Nick can be a difficult person. He sometimes behaves as if he's the only one with problems.