working

Hello, teachers!

Would you please tell me if these are acceptable?

1-1. Two years ago I first met Jane, working at a hospital. [Jane was working, right?]
1-2. Working at a hospital two years ago, I met Jane. [I was working, right?]

2-1. I happened to know Mark, working at the construction (site) of the building.
2-2. Working at the construction (site) of the building. I happened to know Mark.
- Is the expression correct: to work at the construction (site)?

Thank you very much.
Peace!

You can work at a construction site, but you can't work at a construction (if you mean 'construction site').

I was thinking that under some weird contextualization "working at a construction" might just be possible, but in that case it would not mean the same as "working at a construction site".

"construction" can mean a grammatical construction, for example.
It's possible that if you are struggling to study how relative clauses work in English, for example, you might be said to be "working at a construction". This is certainly far-fetched, of course.

More likely, the meaning of "construction" that could be used is the action of putting something together. "Don't disturb your brother. As part of his homework in math he is working at the construction of a geometric proof." This is also somewhat far-fetched.

In short, I included the parenthetical remark just for completeness - not to say that "at a construction" is wrong (even though its use is severely limited), but rather to say that it cannot be used to mean "at a construction site".

Hope that clarifies things.