"It's too late to go shopping. The shops are open only until 5:30. they will be closed by now."
First: what is closed here? an adjective?
Taking the italic part into account, there has been obviously mentioned the fact that if something happens, then we use by. Nevertheless, in my original question, the following phrase is just a statement not an action, so why don't we use until?
"Closed" represents a state, not an action.
My biggest and most important and specific question:
My specific question, now, is about the fact that considering the following explanations, and as being closed is just a statement not an action, why does my original sentence use by rather than until?
The followings are extracted from the book English Grammar in Use:
Something continues until a time in the future:
Fred will be away until Monday. (so he'll be back on Monday) I'll be working until 11.30. (so I'll stop working at 11.30)
Something happens by a time in the future:
Fred will be back by Monday. (= he'll be back not later than Monday)
I'll have finished my work by 11. 30. (I'll finish my work not later than 11. 30)
C. You can say 'by the time something happens'. Study these examples:
It's not worth going shopping now. By the time we get to the shops, they will be closed. (= the shops will close between now and the time we get there)
. . .
UNIT 119 By and until, By the time...
A. By (+ a time) ='not later than':
- I posted the letter today, so they should receive it by Monday. (= on or before Monday, not later than Monday)
- We'd better hurry. We have to be at home by 5 o'clock. (= at or before 5 o'clock, not later than 5 o'clock)
- Where's Sue? She should be here by now. (= now or before now - so she should have arrived already)
You cannot use until with this meaning:
- Tell me by Friday whether or not you can come to the party. (not 'Tell me until Friday')