the differences between before and until

[shirley_sun227]

I'm a bit confused these days. In some cases, "before" and "until" are interchangeable with a slight difference of their focus.
e.g. The woman worked in the factory until/before 1990.

I will wait for you until you come back.
Apparently, this sentence is correct. I'm not sure whether this sentence is still gramatically correct if we replace "until" with "before". I know it sounds a little bit awkward and every person I meet keeps telling me it's wrong, failing to give me a convincing explanation of why it is not acceptable.

I would also like to know under what circumstances are "before" and "until" interchangeable and in what cases can only one of them be used? thx in advance:angel:

 

[5jj]

I'm a bit confused these days. In some cases, "before" and "until" are interchangeable with a slight difference of their focus.
e.g. The woman worked in the factory until/before 1990.

They are definitely not interchangeable here.

If she worked in the factory until 1990, she began work before 1990, and continued to work there for an unknown period of time. . She stopped work in 1990.

If she worked in the factory before 1990, we do not know when she stopped working there, but we do know that 1989 was the last possible year.

 

[Pokemon]

The choice between 'before' and 'until' much depends on the aspect characteristics of a predicate verb: whether it indicates an instant action, or a state or process.

He came home before noon. (instant action)
He worked until noon. (process)
He slept until noon. (state)

Another factor is what your focus is on: what happened, or how long it lasted.

He was playing/played the piano before mother came. (What was he doing?)
He played the piano until mother came. (How long did he do it?)

 

[shirley_sun227]

They are definitely not interchangeable here.

If she worked in the factory until 1990, she began work before 1990, and continued to work there for an unknown period of time. . She stopped work in 1990.

If she worked in the factory before 1990, we do not know when she stopped working there, but we do know that 1989 was the last possible year.

Thank you for your detailed explanation for the differences between "before" and "until" in the example sentence.
How about the following sentences?
I will wait before you come back.
I will wait until you come back.

 

[shirley_sun227]

The choice between 'before' and 'until' much depends on the aspect characteristics of a predicate verb: whether it indicates an instant action, or a state or process.

He came home before noon. (instant action)
He worked until noon. (process)
He slept until noon. (state)

Another factor is what your focus is on: what happened, or how long it lasted.

He was playing/played the piano before mother came. (What was he doing?)
He played the piano until mother came. (How long did he do it?)[/QUOT

"Wait" indicates a state. So you mean it can be used in both sentences with different focuses.
I'll wait before you come back.( What will I do?)
I'll wait until you come back.(How long will I wait?)

 

[Pokemon]

The choice between 'before' and 'until' much depends on the aspect characteristics of a predicate verb: whether it indicates an instant action, or a state or process.

He came home before noon. (instant action)
He worked until noon. (process)
He slept until noon. (state)

Another factor is what your focus is on: what happened, or how long it lasted.

He was playing/played the piano before mother came. (What was he doing?)
He played the piano until mother came. (How long did he do it?)[/QUOT

"Wait" indicates a state. So you mean it can be used in both sentences with different focuses.
I'll wait before you come back.( What will I do?)
I'll wait until you come back.(How long will I wait?)

No, the first sentence 'wait + before' is wrong. That means the second factor works only for processes. With states you always have to use 'until'.