When/Before Sarah arrived at the party, Paul had already gone home.

[kadioguy]

Context:

Sarah went to a party last week. Paul went to the party too, but they didn't see each other. Paul left the party at 10.30 and Sarah arrived at 11 o'clock.
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So:

a. When Sarah arrived at the party, Paul had already gone home.
b. Before Sarah arrived at the party, Paul had already gone home.

Are both of them acceptable?

 

[jutfrank]

In b). By the time is much better than Before.

a. When Sarah arrived at the party, Paul had already gone home.
b. By the time Sarah arrived at the party, Paul had already gone home.

Now they are both very natural and have slightly different uses.

 

[kadioguy]

In b). By the time is much better than Before.

a. When Sarah arrived at the party, Paul had already gone home.
b. By the time Sarah arrived at the party, Paul had already gone home.

Now they are both very natural and have slightly different uses.

I was exhausted by the time (= when) I got home.

https://dictionary.cambridge.org/dictionary/english-chinese-traditional/time

So "by the time (= when)"?

 

[jutfrank]

So "by the time (= when)"?

Be careful—the above is only very loosely true. They have different uses.

 

[kadioguy]

Be careful—the above is only very loosely true. They have different uses.

What different uses are between them? Could you tell me?

 

[jutfrank]

What different uses are between them? Could you tell me?

By the time has the effect of intensifying sequence. That's why it's used so effectively in past perfect sentences which express a sequence of events.

This normally translates into a difference of focus. Let's compare again with When:

a. When Sarah arrived at the party, Paul had already gone home.
b. By the time Sarah arrived at the party, Paul had already gone home.

In a., the focus is on the event in the first clause whereas in b. it's on the event in the second clause. This means that the fact that Paul had already left is more significant in sentence b. The use of By the time directs the reader/listener's focus to the other clause.